Excessive Debits On My Bank Account

I signed up for the price lock offer in Oct 2017 & DSTV has been charging me double the premium service amount for several months in addition to debiting me 4 times the subscription in a single month. In addition to holding excess credits on my account, they disconnect my service too & when calling in they rectify as the account is not showing as in arrears - I've made several calls & sent emails over the past 3 months to get this resolved with no success & they've again disconnected me for the 2nd time this month