Rain South Africa, deducting money from my bank account without consent even after deactivation of sim

Rain is a bunch of ******. I activated my rain sim card on the 19th of of July and paid the recommended R250 for 4G. Since then, I never managed to go beyond the google home page. Contacted support many times but the problem persisted. So in August I decided not to pay the R250. Surprisingly on 1 September they deducted R80 from my account and when I called call centre they said its service charges for having access to internet. Shocked by that I asked them t deactivate my account and they referred me to their web page. I deactivated my sim the same day but to my surprise on 1 October, the deducted R250 from my bank account. I went on my online account to remove my banking details there but there is no option to remove banking details. I called them and they said they will contact me... no one has contacted. These people are running their business on ********** activities. Why are they deducting my money without my consent?