No refund of selling fee, *******!

I'm a registered user on Bidorbuy since yr 2000. Early Dec 19 I sold a watch on Bidorbuy, when we sent the watch in for a service we were advised that it was a replica, we advised the buyer accordingly and at the buyers request the transaction was cancelled and we refunded the client. We have been trying to obtain a refund of the selling fees of R604 from Bidorbuy since then, at their request we have sent all the communication between ourselves and the buyer, emails, WhatsApp screenshots, etc... all to no avail. At their request we asked the buyer to email them confirmation that he has been refunded in full... no avail. Today (5/2/20) I received an email from Ndivhuwo Denga advising me that a refund of the selling fees is not possible and referred me to their terms and conditions. I feel this is not fair, not ethical, not legal.... the watch was sold in good faith and when we established that it was a replica, at the clients request, we refunded it. Likewise the selling fee for that transaction should be refunded. This is nothing short of highway *******!!!! :(