Unauthorised debit order

I signed up for DSTV two months ago, and paid my subscription via the Self Service website the 1st time and everything was fine. Friday (24.08.2018) I wife logged into the Self service portal to pay them, and saw that the amount owing was R1007.24 - so she paid that, never received an statement or invoice from them stating what we are paying. Saterday evening, I receive an sms from my bank saying that the amount of R1007.24 was deducted off my account for Multi-choice (never signed an debit order consent form) so where did they get my banking details from. I immediately phoned customer service, and when I spoke to the gentalman, he said that he can't see on the system why the amount is so high and he will take it up with the accounts department. In my eyes, that is ***** as we NEVER gave them consent to debit my bank account, and now we paid them double as my wife paid them on the 24th August and the deducted the money of my account. I want my money back from them now! This is *****!