Fraud

I want legal advice, I want to proceed towards filing a case. Its regarding an online reselling platform to which I intended to sell my laptop 3 months back. The online platform shows a business model, wherein the price of my gadget was quoted as 18000. The pickup was scheduled and my laptop was picked up on 27th february 2020. Now its been 3 months and the company has'nt credited my payment of 18000. Everytime I mail/contact them they say the laptop is lying with their courier partner who picked up the laptop and they are not able to check it up as they have not received it. And now they're giving excuses that because of lockdown the payment is lingering but the courier services has already been resumed (already 20 days past) and also the laptop was picked 1 month before the lockdown even started. I feel they are doing this fraud with other customers as well as the reviews of the company is bad on google (I checked later on). I have a feeling that they don't have any intention of processing the payment. As evidence I have a video of the laptop at the time of handover and all mail trails. Respond what can be done in this case, as they have wasted my time, caused agony and executed fraud.