Vodacom is so unfair

On 26 July 2018 the evening I realized that Vodacom deducted the amount of R1640.93 from my account which was incorrect. I contacted them on the 27th of July 2018 to query why and what the amount was for. Losefe the guy that spoke to me that day told me that It looks like I was overbilled and he will have to speak to one of the managers and he will phone me back before 9h00 which he did. he informed that the call has been logged and the money will be paid in to my bank account 1 - 7 working days. On Monday the 13th of August I phoned Vodacom again only to hear that according to them the call has been resolved. I was very upset and very surprised and insisted them to go look on the system what happened because I haven't received my money yet. The lady that helped made sure that Losefe phoned me back the same day. He apologized and told me he forgot to send the query. I told him I am not happy and I want to speak to his manager, the manger was not in according to him but a team leader Olga phoned me back and assured me that she will speak to Losefe's manager because he did not do his work properly she also assured me that she will phone me back on Thursday to follow up but I will receive my money no later than Friday. On Thursday I received a call from Losefe to inform me the claim has been approved and I will receive the money by Monday. Today I phoned again to follow up because I haven't received my money I spoke to Phindile Zibi who told me the money will only be in my account form to day 1- 7 working days and that the amount has changed because they will deduction my installment for August and I am not very happy with this. If I was 1 day late with my payment my account would have been suspended but now that I am waiting for my money I have to hear "unfortunately mam this how it is" this unacceptable. From to 27 July 2018 till 21 August 2018 and still have to wait 7 working day for my money????? I cant seem to deal with this