I got a bridesmaid dress SERIOUSLY overhauled here because the bride ordered them in another province and mailed them out to us. It arrived about 2 sizes too big and needed far more than a simple hem job.
The woman was a bit stern, but she knew what she was doing and the dress turned out perfectly. It's a bit pricey, so I wouldn't go here to get pants hemmed, but for the complicated or important stuff, this is the place to go.