Locked into another Two-Year Contract with no Added Benefit

In July 2017 I received a call offering me new deals on my phone and data contracts as I had gone onto month-to-month since my contract terms were up. I was mostly interested in the phone contract that I was offered but I was also told that I could have reduced rates by entering into a new contract for my data plan. I was told that the new contracts would be effective from the start of August 2017 and I agreed to this. However, I noted that I received extra data and minutes (in line with the new contract) on my phone contract from shortly after the call. I called customer service as I was not supposed to receive this until August and was told that there was nothing that could be done until I was invoiced. When I was invoiced, I was double-billed for the month of July (I basically paid for my old and new contract on one line for one month) and upgrade fees had been added on for both contracts, which were not supposed to be added on. I was also still paying exactly the same fee on my data contract but was locked into a two-year contract without any benefit and had to pay an upgrade fee for that. I called customer service multiple times in late 2017 and was either told that I was in the wrong department or was put on hold for long periods of time. Furthermore, I had to reexplain the situation to every person I spoke to (and there were many).

Eventually I was refunded for the upgrade fee and double billing for July 2017 on my phone contract. However I have still yet to be refunded for the upgrade fee on my data contract and I am still paying the amount I was paying before I "upgraded" and got locked into another two-year contract. I would very much like to be refunded for that upgrade fee and either go back to month-to-month on my data contract or be switched to paying the promised fee per month (and refunded for the difference that I have been paying since "upgrading").