Horrible service overcharging my installment 😡

Horrible service😡 TFS is charging me R690 instead of R69. I call them the consultants tell me they escalating the matter. That was in April. No response. I send an email beginning of May and they respond saying they are escalating the matter. I call them after a week still not resolved. It's been two weeks still not resolved. Month end they gonna deduct 600 more on my installment once again I don't understand whether they think I grow money. I'm so frustrated horrible horrible service