Charged for usage which I did not use. Promised credit but no credit was done

I contacted Vodacom on around the 25th Aug 17 to advise them that there were charges to my data account which was impossible. I had 700mb data on 2 days prior and on the 25th my account had gone over to R600. I barely used the router. They advised me that they could not log a service request. I then did not use the router for 2 days. When I logged in online to check my usage the account went up to R800. I contacted them again and they disconnected the internet services. I then did not want to use the sim until they sorted out the issue. They advised me that I would be credited as a sign of goodwill. Yet I know this was not my usage. I then had them activate the services on the 16th of September after being credited. After that I then received an enormous bill for this sim and yet I did not use the sim for the entire month of September. After a while I spoke to one of their consultants that confirmed that I would be credited for the R2400 charge which I did not use. Today I was advised that they will not credit me. I honestly did not use this data. Further to this they have added on Vodacom services which I did not ask for. I noticed this when I looked at my account on the 25th of August and was promised that this would be cancelled only to be told yesterday that it was never cancelled and I need to cancel this from my side. They are lying to their customers. How can you tell a person that a credit will be done and then advise them that this will not be done. How can you advise me that services were removed but it was never removed. I know that this was not my usage and have checked the Imei numbers which does not match up exactly. I am being promised by everyone that they will call me back and resolve the situation but they never resolve it. Now I am being held responsible for charges which I have not used!!! I will await the end of my contracts and will move to another service provider. Be warned to take out contracts with them. Their calls are being recorded yet they do not take the responsibility when their staff promise refunds. I am utterly disgusted!!! My account on average is R1500 per month. They will now lose a customer that they had for years for R2400. They must have rather done the maths and listened to the voice recordings!!! I even received a call from their data department asking me to change my password. When I explained everything to her she agreed that there must be a mistake with the account. People make very sure when taking out contracts that is open plan. Vodacom will make a plan to charge you for things that you did not use or for services that you did not request.