They will not send out a new modem unless something is wrong with this one.
I might try the direct forum and see what they say.
Seriously man how is not having slow internet not something that is wrong with your service. Like other have mentioned go to your local service station and get your modem swapped out for a DOCSIS 3.0 modem.
Or you can go buy your own modem and avoid the rental fee. So seriously you need to go do that before complaining more about your internet not working. Lots of people have problems with old modems.