Being Charged for old Contract after upgrade

Firstly I have not been receiving my monthly bill. For the month of March I was billed almost R600 and my contract was R260. After calling in and querying this, I was told that I went over my data limit and was billed additional charges. So I accepted this and made payment was made. I have taken my contract upgrade beginning of March and at the end of April I was billed extra again and still after requesting statements several times I have not received one. I was billed an amount of R480 resulting in another one of my debit orders bouncing. The bouncing fees are in the region of an additional R200. I called Autopage five times today and the first two times resulted in getting transferred from department to department with no help. The third time they said that it will take 2-14 working days to be refunded which is not acceptable, each time throughout the day I have asked to speak to a manager I was told that he is not available, what kind of service is this and they suppose to be a service provider. the forth and fifth time I was told that because it was an early upgrade I have to pay for both device. this is the first time that I am ever hearing of this when it comes to upgrades!