account not credited for 4 months

I bought a laptop on contract in Feb 2019 for my studies. I didn't use the laptop the first 2 weeks because I was waiting for my books to arrive so that I can start my assignments. At the beginning of March I took the laptop back due to the fact that it didn't have the office package installed which was one of the reasons I wanted the laptop due to the fact that all my assignments needs to be done in word or excel. I got the laptop back after 3 weeks. Then only to realize that evening that office was still not loaded. I took the laptop back again and only received it back after weeks again, which resulted in me into having to move my semester to the next terms which costs me extra R2000.00 the 3rd time I received the laptop back office was still not loaded. I gave the laptop and ****le back due to the fact that it is of no use to me, since then I have been having a constant battle with the R1600-R1800 that keeps on going off my account after I was told that I could give back the laptop due to this been Vodacom's error. My account needs to be in credit for 4 months now but still every month the costs keeps on going off. I go every time to Chatz connect in Carletonville and every time I am been told that my account was credited. This is really becoming a huge issue for me and needs this to be sorted out ASAP.