Over billing

I filed a complain about Autopage recently over blling me and after 2/3 weeks I got a call from them. They said they will give me credit for what happened. They sent couple of sms about my credit. Still this month there are doing it again. I all started when I took a contract with them. I told the Nelisha the consultant that my contract must never exceed the package I signed for. Of which it was 200 sms, 100min of airtime and 300mb of data. After exhausting it I will have to buy over the counter to top up. My contract is supposed to be R420 or little more, but from May it went to R1144.65 and also after I was promised credit went to R1127.11 and I don't know where these figures come from