Why is the billing different every month where as my account is up to date

So a I took two pricelock accounts with DSTV ( premium and compact) about a couple of months back and they were debiting my account alright until I added the compact and I opted for making manual payments at the branch or pick n pay. On Feb my services got disconnected and I was asked to pay 1800 to get my account up to date.

I then paid an amount of 1900 rands at Checkers on the 04/02/2019 and my account was up to date. On the 25/02/2019 I paid 1000 via EFT (for the premium) and 554.00 on the 01/03/2019 at Pick N Pay and again month end of (March) I did the same and my account was update as I called in and my balance was 0.00. I called in today to inquire about my account and I was today that the amount due is 1840.00 as to how it got there I seriously don't know and when I asked the agent I was dealing with to explain to me as to how it got the she was clueless and it was not funny.

Can I please have matter resolved as I find it TOTALLY RIDICULOUS

You need to train your agent Sebenzile cause she is really clueless to what she is doing