Cell C won't let me make me arrangements to ensure debit order continues

I just called Cell C customer care to change my banking details for my debit order with them. I am told that I am not able to do this until my new bank account is 3 months old. How is this possible? This is unacceptable. So many people do not pay their dues but when I want to make arrangements to ensure that I meet my commitment I am told I am not allowed to do so. I am quite stunned... Unacceptable Cell C.