My account has been incorrectly debited AGAIN

This is the third time that Cell C have incorrectly debited money from my account. The first time, they debited R8999,33, the second time they took another R8999,33, and this morning I wake up to another two debits going off of almost R2000 each, and I have one pending for over R3000. They phoned me last week and told me that this problem was cleared up, but this is obviously not true.