How to Proceed

I was with Telus previously but moved to an area that Telus does not serve so I had to cancel. I returned my equipment via Purolator and thankfully (at the urging of the Purolator Agent) I kept my receipts.

About two months ago I recieved an email from ARM saying that I owed money. Called Telus and since I had the proof that I returned the equipment they removed the debt and I was told everything would be fine. A few weeks ago, I got a notification from my bank that my credit score changed. It was from the collection agency for Telus. Called Telus again and was told that they would rectify the mistake. About a week later I checked my credit score and it was fixed. 

This morning I woke up to another notification from my bank because there has been a change in my credit score. Again, it is from Telus but this time it is from a different collection agency. I am at my wits end and would really like some advice on how to fix this.

Each time I have called Telus they have refused to send me proof that my account balance is at zero and I have been asked to trust them. Obviously the trust is gone. How do I proceed?