Unilateral Credit Increase

I have now come to the end of the road with Foschini with whom I have had an account for over 35 years!!! The continue to send me text messages which read that I owe them NIL. That is NOT correct so I do not know how they can possibly balance their books!!! I owe well over R8 000 if not more. Now I received a unilateral text message congratulating me on the increase they have given me on my credit limit. I DID NOT ASK FOR SAME AND NOR DO I WANT SAME!!!! This retailer is staring to annoy me now!!!!