MTN deducting more than bill

I am very disgusted with MTN. On 4 May last year MTN deducted a double amount from our bank account, at least they paid it back on 6 May. On 1 Dec MTN deducted almost double again, now they are spinning stories about “ pro rata data” . I am going to complain about this on every forum I can, still waiting for that money to be paid back after numerous phone calls and branch visits..... Queries, *** 3Jan, *** on 14 Jan *** on 18 Jan . I am going to cancel all my contracts with MTN as soon as I can, it seems they simply decide how much they want to take and then simply deduct it from your account.