Fraud by online shopping site

Dear Sir/Madam, On 10.07.2017, I had placed an order with gofreshh.store for fresh meat and fish items worth Rs.943/-, which I paid for online. After waiting for 5 days, when I didn't receive the items, I got in touch with their contact person/s and was told that it would be delivered in a couple of more days' time. Since it was an inordinate delay and they were unable to specify when they would deliver, I asked them to cancel the order & refund my amount via the same payment gateway, which they promised would be done right away. However, till date, after repeated phone calls and whatsapp msgs, I am yet to receive the amount I paid. For the past several days, they have either disconnected my calls on seeing my number or ignored my repeated pleas via whatsapp to resolve the matter amicably. On calling them from different numbers, when they picked up, they cited unrelated reasons as deaths and accidents in the family, etc. or that the the company was going through 'some problem' right now. Seeing that they were citing utterly unprofessional instances for not keeping their promise and deliberately avoiding me, I decided to officially send a notice to them, demanding Rs.943/- as well as a compensation of Rs. 50,000/- for the distress and agony they had caused me all this while on . But it seems that the address provided in their invoice or website (which now is suspended), all proved to be wrong and my speed posts are coming back to me. In such a situation, please guide me what stern action I can take against them for the fraudulent activity. I do not want to let them off so easily. Thank you.