Billed $268 for equipment never installed, admitted error, still sent me to collections

So a Telus SmartHome Security tech was supposed to install a security system at my place. Guy shows up, realizes he doesn't have the tools to check for wires behind the walls before drilling to install the outdoor camera, and just leaves. Dude seemed completely lost.

I called Telus right after to cancel because honestly this wasn't serious at all. Went with another company. No equipment installed, no service, nothing.

Telus still bills me $268 for the security equipment. After 2 hours on hold they finally admit their mistake IN WRITING and say they'll submit a credit and notify the collection agency.

Spoiler: that never happened. Still getting collection notices and threats about my credit score.

Their customer service is absolutely useless and I'm not spending entire days on the phone to fix THEIR mistake.

I filed with CCTS but Telus is contesting their jurisdiction because it's security not telecom.

Anyone been through this? What worked for you? I'm in Quebec.