Worst service ever

This is my first cell phone contract and it will be my last. From day one there has been problems. They entered my banking details wrongly into the system and charges me R220 because the debit order did not go off even though the agent did not put in the banking details I provided him with. I paid my account via EFT and my account is up to date. They debited my account on 30 April and now they are trying to debit my account again on 1 May. I have complained 4 times and promises were made that it will be fixed. PATHETIC