Netstar - an exercise in futility!

Netstar - Due to dissatisfaction with their service and unavailability to communicate telephonically with Netstar I e-mailed them on 25/01/2021 with instructions to cancel my contract. Their reply was received on the 11/02/2021 whereby I was informed that since it was a 36 month contract I would have to pay a settlement fee of R2119.90 payable forthwith. I immediately rep**** to their e-mail requesting them to disregard my instruction to cancel and expressed my intention to carry on with the contract until it ended and requested acknowledgement. On the 27/02/2021 I received yet another e-mail for Netstar informing me that in order to cancel my contract a settlement fee was payable - this time for R2052.53. Once again I rep**** immediately and referred to my previous e-mail and once again indicated my intention to carry on with the contract. Imagine my dismay and surprise when I noted that Netsar had unilaterally and *******ly had gone ahead and debited my account with R2052.53 on the 01/04/2021!! What do I have to do to get Netstar to comply with my request??