Arrears

I have been on a explora pricelock account in May 2017 i settled this account and from June 2017 i payed the R360 on the account for compact subscription. I never received any information about my account from multichoice thats why i continued paying the R360 until last month when they switched of my decoder without any warning and when i cobtacted them suddenly there was arrears of R1300 after all the months of nothing. After sending several emails with the settlement letters to different departments they rectified it but now they let me know im in arrears with R1900 for paying only R360. What am i to do because no one ever got in contact with me since last year that i started paying that amount to inform me that im in arrears. And my account on selfservice always showed an advance.