Conseco-Greentree Mastercard-Doesn't correct fraud charges

On May 27th,1999 a fraudulant charge appeared on my master card bill. I paid the entire balance minus the disputed charge. My next statement still showed the disputed charge plus they charged me interest on the disputed amount. I have written several letters & called several times. I have been told it takes many months for them to even respond. It has now been nearly 1 full year and they only say they will get to investigating when they get to it!! The month after I was charged interest I decided to pay the disputed amount plus the interest they charged to keep matters from getting worse. They obviously dont care about customers. I know disputed charges are suppose to be resolved within a time frame much less than 1 year. Who regulates credit card companies? When the billing was handled by Greentree it was ok but Conseco has a terrible attitude and I'm certain hasnt done anything to investigate my dispute. (The charge in question was billed by a company in Brussells Be!!)