Billing Disputes unresolved

I took out a Cellphone contact in Nov2017, Telkom did the pre-authorise debit order and have go confirmation notifications of its success, I was also clearly informed that the initial debit order would be credited against my account. I have not been credited these funds for over a year now with numerous billing disputes logged every month or so, I get the same run around each time I call about the disputes. (Note: at the same time we acquired cellphone contracts for my wife and mother, both of which were credited the initial debit order so there is president for this credit to reflect). I have spoken to Billing "managers" who say someone will get in contact with me, but to date not a single call back. I have also been given the run around to contact the sales department, they just refer me back to the billing department. Billing department has also sent a few mails to the back office asking them to look into it, that too does not help. what am I to do? As I see it: Telkom are retaining payments without allocation, I think there is a word or two for that "*****?" "Theft?" ?