Discount taken *******ly by Bankmed

I submitted a claim to Bankmed for which I had paid. Bankmed processed the account to refund to the service provider - an amount of R12044.20 when I brought it to the attention of Bankmed that I had paid for this service and because I had paid cash immediately after the service Bankmed now only want to refund me R10966.60. Bankmed did not make the cash payment and therefore are not entitled to the discount, particularly as there are many lines on the account which Bankmed did not refund. I am the one out of pocket not Bankmed!!!!!!!!!!!!!!