If you have a DOCSIS 2.0 modem ( and i should remember because you have said it here before ), then chances are just a modem swap should do it. If you upgrade.
On another note, you could work it a little , and grab there highest package for a month to test it out, and if your not satisfied , then just call them up and switch back. In that case however , you would have at your disposal , a DOCSIS 3.0 modem. Which would clear up any issues you might have with the modem. If any.