Draining a sink?

https://www.hometalk.com/diy/-24007102

Try baking soda and vinegar

Try a toilet plunger.

I've had the same problem- what works for me is: pour a few cups of boiled water down the drain, then pour about 1/2 cup of baking soda , then a cup of vinegar. After ten minutes, pour a few more cups of vinegar. Sometimes, your sink will be too clogged for the boiled water to drain, in that case- use less water and pour the vinegar/baking soda even if it doesn't go directly in the drain. Once all of that drains, repeat from the beginning one more time.

Have you tried the pluming snake? Also if you have spot on the side of house that is a drain plug, you can open that up to snake it that way, not just down the sink.

Use liquid Cascade, pour down drain followed by boiling water. Let set. I had to do this a couple of times but now I don't have any drain issues and it's easier than snaking and alot less smelly.

I see your in Canada....are you sure it's clogged....it might be frozen. Back in 1977, in Indiana, we had this horrible winter, everything was frozen and covered in snow, 10-12". Then the sink started running slow....slower....till nothing went down. Put everything down the drain to get it to go but , nothing. I even plunged it, thought it said not to. Nothing still. Then I moved to Ohio! LOL!

Looking back the heat tape could of quit working. It was an old Victorian house and drafty, on the top of a hill, out in the boon docks! Ohio was cold to but at least you could see lights which meant civilization. Hope you get your pipes working!