Incorrect Billing/Breach of contract

In November 2017, I was contacted by a sales representative who introduced themselves as T-connect, asking me if I would be interested in a WiFi- router from Telkom. A special offer of R99 per month for 24 months was presented to me which included, 500mb+5000G Telkom +10 000G night. The person never explained to me that the router offered would have network problems depending on the area I am residing. After receiving the router, I had endless problems connecting and phoned them several times to assist but still it could not work. I took it to a Telkom store for assistance but they also could not assist. During the month of December a total amount of R426.85 was deducted from my account which I then reversed since it was not what we have agreed on. On the 3rd of January 2018 I phoned T-connect to cancel the contract as it was not working for me. 1st I could not use the router and 2nd they were deducting far too much money than what we agreed upon. The consultant arranged for the pick up of the router and assured me that he was cancelling the contract for me. The was promised that the router was gonna be collected 3 days later but on the 3rd day their courier, Ram couriers, phoned me to postpone the collection to the 8th of Jan. The collection never happened until I made several calls to both T-connect and Ram couriers. Eventually on the 12th it was collected. Today, the 15th, I received a notification that another R426.85 was deducted by Telkom Tel K. My question is why are they still taking money from my account which we never agreed on and when the contract is also cancelled? I am going to the bank to ensure my money is returned and they must please stop doing this transactions. I want nothing to do with them.