Limit increases without approval

I have a store account with Exact, Foshini group, no problems there. However they have been increasing my limit without my approval, and last year I went to one of their stores and asked them to decrease the limit, only to find out today that they have increased and it has more than doubled from what we agreed on. Should anything happen to my account, I mean should my card be ******, whose is suppose to be liable? Especially now with data leaks. I can't be going to their stores to ask for the same thing over and over again. I realised that my limit has more that doubled last week when I was making a purchase later at home.