Unautherised debit orders

I have an account with Supersonic Mtn now since 2018 and ive paid my account every month by eft ever since last month they just decided to debit my bank account with double the amount even after Ive paid them . I then went to the bank and did a reversal and this month the same thing happened . Im not very happy with this service even though every now and then the service will be offline and thats not what I paid for . I would love to cancel the service and really open a case of ***** against them as they are drawing unautherised monies feom my account. Please people do not support these guys . Tereble service