VODACOM CONTRACT

I took a contract with vodacom in 2019 around April/May. According to the contract they should be deducting around R500. However since February 2020 they have been deducting R700+. One of their consultants called and asked if I was still happy with my contract and I made her aware of the changes and she looked and said I have been given an extra 5gb (that I have not consented to and have not used). I use my Voda Sims on nonsmart phones. So there is no way I used that 5gb. Even if I was the Sims on a smart phone, I was unaware of this 5gb. I wrote to their Facebook several times, no assistance, I called 082 135 no assistance as they don't pick. I then went to the nearest shop and I was shown this 5gb upgrade. I was then requested to write a letter to which the store would send to relevant department on my behalf and I did that (its almost a month no response). I then wrote again to the Facebook page showing them that I went to the shop about this matter and the Facebook administrator advised that I email *****s department. I emailed the department and attached the letter I had written at the store. I got a response from someone by the name of Thabo and they claimed that there is no 5gb appearing from them I should go back to the store. I emailed back, responding that at the store they sent my letter to a department that has not even responded. How do I trust this? After my complaint, vodacom continues to deduct the amount and my complaint is not resoved.