Unauthorized debit order amount

I have a contract phone with Telkom, the initial debit order amount is R389 which get debited on the 25th of each month. This month they decided to debit R591 which i don't know why they did that, i disputed the amount then made manual payment of the amount on contract. To my surprise this morning they debited another R202 which I don't know what it's for. And again when i call their call center I don't get assistance, after this phone I'm done with them wat hurt the most this is my third upgrade with them but im so done with them