MTN - BANK ACCOUNT NOT CHANGED!!!!

I have tried so many times to change my bank account. MTN is the only reason I cannot close my bank account. I have also gone into a branch (Walmer, Port Elizabeth) to discuss this, I have called about 5 times no one is getting back to me. These are the following names I have spoken to and not done anything about it. Walmer Port Elizabetg - Coran Primerose Leon Sithandille Ntaka Sipho Ngcobo Zama Bhengu