There is a limited set of paths into Montreal. It's not uncommon for there to be issues along the routes during times of high traffic. It's not isolated to just this game. It happens all the time all over the place.

The last mile ISP's keep selling higher bandwidth at the endpoints, but their upstream bandwidth is still the same as it was when we were offered half the bandwidth (or less). Effectively, they've just stuck bigger funnels onto the same sized hose, feeding into the same sized bucket. Eventually, the funnel overfills and starts sloshing crap all over the place. When you call them, they look at your local connection and see everything is fine on your end and wash their hands of it all. What they don't do is look at what happens at their exchanges with their routing partners or beyond, which is where the choking is occuring.

In all fairness to the guys that answer the phones though, they aren't typically empowered to look further into things than your local segments. What you need is a higher tier of support--the industry term for that layer is Tier3, but some locals may refer to them as Engineering or simply their Admins. In some cases, you have to push to speak to a supervisor before you get someone who understands what you are asking...unfortunately. Again... those helpdesk guys on the phones often have their hands tied on these matters. You may need to push for someone higher up the chain. I've found I fair better when I use the online options to contact Time Warner. Might be worth checking out your ISP's support portal for an online contact option.