Discounts being added to your bill!!!

I received a call for an upgrade of my Wi-Fi deal, I agreed to the upgrade, it was for less money. I also agreed to the 2 new contracts for tabs and top up data. I have paid such a lot of money for Jan and Feb's invoices. I understand you need to pay a pro rata fee because of the data and charges etc. I just can't seem to understand why on my invoice there is a line item called discounts, but every amount listed there is added to my bill as supposed to being subtracted seeing that its a discount. I have disputed the same invoice twice and received case numbers but nobody called or assisted me in any way. Today my account was debited with the full amount of the invoice I was disputing. I'M EVER SO SORRY I AGREED TO UPGRADE MY CONTRACT AND SUBSCRIBE TO 2 NEW CONTRACTS WITH TELKOM. I WILL NEVER EVER DO IT AGAIN!!!!!!!!!!!!!!!