This is by far the worst experience I've ever had with any car rental company. The agent was rude, did not to her job in checking that the car was damaged (had to come up and tell her as she didn't take a look at the car whatsoever) and I was given a filthy vehicle that had dirt in the floor mats and bird poop on the chair in the back! Before I picked up the car, I asked what the 'other' charges were on my bill (amounted to about 1/3 of the price) and she didn't know.
When I mentioned the car was dirty and had a strong smell, she told me I was wrong because she cleaned the car herself.
Any attempts to fix the situation with the location were fruitless as I was told multiple things by multiple people and nothing ever came of it for weeks even though I called back once a week to try and discuss the situation. I finally went through Avis' customer service who solved the issue and they provided excellent customer service.
I'd like to stress the following: as a company Avis is great, it's this particular location that seems to employ rude employees and is owned/managed by a woman whom they called "Mrs. Mary" who does not seem to value her customers or giving good service of any kind. There are plenty of other Avis locations to rent from in Montreal, please choose one of them instead!