Rogers → [Extreme Plus] Wireless has low or no signal

SMCD3GN - bought it outright when they first were offered from Rogers store. Wireless has seemed to stop working. Will they replace this unit for another (refurb?) ? Anybody go through this type of situation.

Lots of people! Have the modem put in Bridge Mode and use your own router.

Seems I recall a very wise man once saying these SMCD3GN Gateways were complete junk. Oh wait...that was me!!
Now to the issue, if it's still under warranty and you still have your receipt Rogers may replace it (yea right) More realistically you'll probably have to shell out another $149.95 and try your luck again or you'll be stuck renting a refurbed Cisco gateway @$7.91 tax inc/month until you're too old to use a computer anymore. You'll have paid about 10 thousand dollars to Rogers for a refurbed gateway by then.
Otherwise Hooter is right, bridge the thing and call it a day. Nobody will leave you hanging out on a limb faster than Rogers.