MasterCare please assist.

I have been trying to resolve a billing issue with Mastercare for 3 months now. I have called, I have emailed, I tried logging a complaint on the Website and couldn't even do that because it generates an error when you try. I spoke to a call centre agent yesterday. She was so disrespectful. That call should be pulled and addressed. I then spoke to someone else, who promised to call me back in the afternoon yesterday and did not. I called again this morning to request assistance. I again get told that the Finance team is unavailable. It will be going on to the 4th month now, where Mastercare will be deducting money from me incorrectly. I still have no resolution or assistance. At least yesterday the 2nd person I spoke to assisted with giving me information on my account - Mastercare have incorrectly added appliances that do not belong to me. There is no proof of me requesting an increased plan. I have emailed 2 people directly in Finance and there is no response, more than once. I have asked to speak to a Manager or Teamleader and nobody is willing to put me through to anyone. Mastercare owes me a refund for the incorrect amounts being deducted, but nobody is actually assisting me with this. I edited my complaint to remove the names of the people I have spoken to and emailed, however if I still do not get assistance I am happy to start naming everyone.