Overcharging on price lock

The ****gersim that is DSTV, I took out a price lock for the new ultra paid an extra R200 in May because of early cancelation for the price lock I took in 2019 and was due in August, Last month I was debited close to a R1000, called to rectify the error and they apologized and credited me back R150 which didn't make sense, this month the app shows I must pay R1200 and at first they said R539 was reversed and check bank statements nothing was reversed and went on to say February and March was not paid that is not true because I have a debit order to avoid drama, I'm sick of being played by DSTV and demand they terminate my contract with them or they must get this in order.