Limit for refund requests?

One of my clients sent a refund request, for the features I didn’t promised, so I denied refund request for the first time. Than he sent another request, I denied. Today he sent for the third time and I’m really tired of this. Now he says it’s a mistaken purchase.

Would you please set a limit for these requests? I mostly approve requests but this one seemed like an abusive behaviour.



I think limit not necessary where we have a specific reason to get refund:
Envato Market Refund Rules. Only under the refund policy customer can get refund. Otherwise Author can decline but Author should to explain customer why decline.

Also Author have Author Support for any unexpected issues.