Double debit my account

Telkom double debit my account and I have asked repeatedly for months for my account to be debited only on the 25th of each month and they have been *****ing me around made my account go into minus because the randomly take off on the 15th yes i owed them but I have paid them now and now they double debited me all i want is my account to go off on the 25th that's it no stress needed I will the the amount but I need my account to be resolved and just be debited the 25th of each month