Cell C keeps suspending account

My dad has a contract with Cell C and has given them his new banking details via phone about three - four weeks ago and up until today they have not saved his banking details on their system! We have called them over 10 times and have given the new banking details and over and over and they unblock the accounts but the very next day the account is suspended again. This has been going on for over two weeks now. We run a business and not being able to use our phone is making us run a loss! Every time we spoke to a consultant they took the new banking details but did not save it and the account gets suspended saying the account is in arrears. Most of the consultants we spoke to have no clue what they are doing! Even speaking to the team leader has not helped us in any way. Please sort this out before we take this matter further.