You need to file a suit for recovery in this case. If your client is a company you need to file case at NCLT

Firstly you should serve a legal notice to him truant advocate asking him to repair the entire amount for the professional services rendered by you along with interest.

If he fails to do so, you will have to file a suit for recovery in civil Court against them in order to recover your money for which all the invoices raised by you would be required.

Also, you can file a police complaint against him for criminal intimidation under section 506 of the Indian Penal Code for his threats.

You have to issue him a legal notice seeking amount for.your service in case it is a company.you can issue demand notice under IB Code, if on notice the person fails to pay the amount you have to file suit to recover the amount.

Further for intimidation you can file a FIR before the jurisdictional police station.

Dear Sir,

Don't hesitate to send out an email if the invoice has not been paid by the agreed-upon date. There's always a possibility that the invoice was lost or misplaced. Maybe the client was on vacation or had a family emergency. You shouldn't instantly assume that the client is a deadbeat because they didn't pay on time.

Send them a friendly yet firm email reminding them that the invoice is past due and you'd like to resolve the issue as soon as possible. Also ask if they have any concerns with the product or service that you provided, or if they need assistance with the payment process.

3. Talk to a lawyer.

When your client is either resisting or ignoring your requests, and you still think the unpaid invoice is worth the trouble, you should involve a third party. But don't ask a friend or look online for help; meet with an actual attorney who will suggest which legal courses of action you can take against the customer.

According to Willis, once you've tried all else, it's best to hire a lawyer to write a demand letter.

"Many businesses and individuals do not understand the legal obstacles involved in collections," she said. "So, if they are a debtor, and your lawyer contacts them, many will just pay without analyzing further."

This is fraud and cheating.  File a complaint against him. If the police refuse file a complaint case against him and send him a legal notice too.

Regards 

Dear Client,

As per facts, Firstly, you have to lodge FIR at the nearest police station against him for the threat to you and give the evidence to Police for that.

secondly, you have to file a suit for money before the civil court where you run your business. 

You may call me through KAANOOM for more detail.

File Summary suit along with all evidence in hand....

1.  Lodge Police FIR against Client, for Threatening, Intimidation, Breach of Trust, Cheating etc.... and request for investigation & charge sheet in court.  IF the police refuses THEN file private criminal complaint in local magistrates court for the above mentioned offences.  The Client may come down for settlement.

issue him legal notice to pay your outstanding  dues

2) if he fails to pay file summary suit under order XXXVII of code of civil procedure to recover your money with interest 

3) also file police complaint against him for cheating under section 420 of IPc 

Any written contract between parities or order placed by client in writing ?

Send a legal notice as advised. The signed contract would suffice. Not having invoice does reduce your leverage.

See you can give a legal notice for payment, raise a invoice along GST for service and demand

Than drop those chats on email, corroborative proof of service deliver and payment due. Issue legal notice for payment. still not paid, summery recover suit will file to recover amount.

Can also try by filling police complaint.

Any evidence of email stating that you have completed the work will suffice

issue legal notice to seller to pay your dues 

2) take legal proceedings as mentioned herein above 

3) enclose copy of contract , correspondence exchanged with the party 

First thing is to send across a legal notice to your client, who has not paid outstanding dues due to you. You can give him a time of say around 10 to 15 days in your notice to clear the dues and thereafter if he fails to pay your dues, you can further initiate recovery suit against him for recovery of money due to you. 

Dear sir, 

As per your query the best plan of action is to serve him a legal notice stating to pay the money along with the compensation for the mental agony, harassment and loss of business occasioned because of his acts. If drafted sufficiently, that would do the job. If mot, consequently we can file a suit for the recovery of money and a criminal complaint can also be filed against the person who has threatened you under appropriate sections of the Indian Penal Code, 1860. 

Hope that solves your query. 

You can contact me for consultation. if any 

regards, 

YUGANSHU SHARMA

ADVOCATE 

You can send a legal demand notice for the money he owes you and initiate further legal steps if he fails to respond or comply with the demands made.

For his threats you can  lodge a criminal complaint with the local police.

For the persisting threats you may lodge a criminal complaint and also for the dues from him you can give a complaint for the offences of cheating and breach of trust, the whatsapp messages can be an evidence for the police to take action.

Dear

You can lodge FIR for fraud, criminal intimidation and criminal breach of trust against your client.

Or you can serve him a legal notice through your advocate for recovery of your service charges from him. 

If he fails to comply with legal notice You can file a recovery suit against him but it will take time to dispose off.

Move a complaint against him to local police for cheating and criminal intimidation along with recordings of threatening

1. As per the information mentioned in the present query, makes it clear that you have a genuine case of breach of contract irrespective of the fact as whether you signed any contract or not as everything was on messages.
2. You should first give him a legal notice (legally drafted) to pay off the dues or you would exhaust/ take the both civil as well as criminal remedy.
3. Then if no reply from him then first file a police complaint about threatening and then file a suit for recovery of dues with interest thereupon before the civil court of law.