Wrong deductions over my account

I’ve been with Tfg from 2017 before they even I ntroduce bash lately they’ve been charging more for no reason I pay monthly instalments last month I paid R970 never bought anything since then nd my buying power was R5912 today they deducted something that I’m not aware of mind you my plan is 6 months interest free nd they’ve been deducting the interest I sent them email they did not respond after few minutes they deducted again meaning they deducted twice today I work very hard to pay that account and I am loyal customer but it seems like they no longer need me