Billing Issues and Incorrect Account Setup

I have been on Telkom's 10gb + 10gb for the past 2 yrs and I have to admit that the service was very good, the upgrade however, which took place at the end Feb 2015, has been a nightmare. I was overcharged R100 for 2 consecutive months and the latest incident is that my 10gb night surfer data is missing which means it was removed from my account somehow. In the past week alone I have spoken to 3 telkom mobile agents who were not able to assist me due to system upgrades taking place at telkom. The month is almost over which means that in the beginning of May I will be sitting with yet another billing issue because I would have paid a subscription for 10gb + 10gb but only got 10gb to use in the month of April 2015. PLS HELP!!!!