So, you mean to say that OP has marked the orders as completed without actually transferring the money and therefore his P2P binance account is disabled?
Usually if one party tries to cheat, binance will take the proof from other party and resolve the dispute. For example, if he has not released the money, the bitcoin or USDT in escrow would not have released so there is no point cheating in binance P2P.
There are 2 options
1. Reporting the account to the customer support
2. Opening a dispute
Reporting the account to the customer support does not automatically lead to opening of a dispute, and they even warn before one makes a report, that, if they maliciously do it, they could face the consequences. I don't think the warning is a result of someone or group of people reporting the OP's account, though.