Mastercard problem

Already 12 years I pay my insurance policies with mastercard,( because as an European I don't have an bancaccount in SA ) the last five years with A en G. Last year in april, A en G let me know they could not recieve my payment. I inquired with Mastercard Europe and they let me know that A en G gave the right cardnumber but a wrong expiration date. I already wrote several mails to A en G about the problem but always get a standard message back. Nobody seems to care or investigate where it goes wrong in the chain. With no other business I have problems with this mastercard. Somebody ever experienced the same problem? I can change to another insurance company but until now I have been very satisfied about A en G.