Vodacom's Mall of Reds incompetence

To say that I'm extremely frustrated with Vodacom is an understatement. In January 2017, I went to upgrade a contract and cancel another line. The guy at Vodacom Mall at Reds said the request was done and I walked away without being given any documents to sign for the cancellation. Month after month I'm being billed additionally and phoned Vodacom only to be told that the line I requested to be cancelled was not cancelled. They said they would call me back, when they did the line cut and I never heard back from them. I have a reference number for this. In Feb this year I phoned Vodacom again and explained, they said they can see the cancellation request was made but never received documents from the Vodacom store at Mall of Reds. They provided me with another reference number and said that to get a refund for all these months I have to go into the Reds Mall store which I did on Sunday. It turns out, I spoke to the same guy that messed up and then asked for the store manager, a lady named Renette. She checked ont eh system and it turns out, according to her, that her colleague had requested to cancel the contract line that was upgraded, which honestly is baffling to me. she said she would discuss with the store manager that was due back on Monday. I have called her ever since and have received no feedback. I'm owed about R4000.00 due to being billed for a line that I had cancelled but was not carried out and instead the wrong line was cancelled.