Customer service

My lines has been blocked all of the sudden even though that my account is up to date. When I called the call centre and the told me that my credit limit is to low that is why my lines has been blocked. I just want to know how can that be possible after I have been with Telkom for such a long time. They also told me that the will escalate my query and a supervisor will get back to me with in 5 to 24 working hours