IIRC, their web site says that if you can't get higher speeds, then they'll just charge you for the lower speeds. Call your sales rep back and see if they can confirm that. I've talked to folks over there before, and they've been consistently very nice and helpful.

When I was considering going to them once, I was thinking about getting them to install an SDSL line, which wouldn't interfere with the normal ADSL line. And then cancel my ADSL service after it got installed. It's pricier, but it might be worth it.