Unauthorised debit order

I bought a car Tata in 2016 I had a contract with tracker which is supposed to run for 3yrs! Then it’s now month to month! I called teacher to cancellthe contract in 2022 now this year I was reversing the debit orders! Now I called again on 3/05/23 to cancel again now they keep taking my money by force! Everytime they increase the amount ! Last month I reversed F369.54 now 27 May they took R429.54 I’m a pensioner I need my money to be refunded! Because the do a debicheck mowing that you can’t reverse it! A debicheck must be aurthorised and I satainly did not authorise it! I need a refund of my money! We are pensioners we have paid you your 3 yrs!