We underestimated how much we were going to spend in Canada and needed to find a currency exchange place. After a little yelping and googling, I narrowed it down to three fairly nearby and reputable and trusted places. Mind you, there are tons of exchange places on St Catherine at those souvenir shops but I didn't know how legitimate they are.
I emailed/messaged 2 of the 3 places and received a msg back within an hr or two from universal currency exchange. They have no service charge unlike some of the other ones and they were located in the underground city. The only downside is the line but 3 out of the 4 windows were open for business and made the line go by quickly. Overall, happy with the customer service.