Replacement modem needed

My Xfinity modem died 2 weeks ago.  It will not turn on, no lights, nothing!  I've been trying to get a new modem since day one with no luck.  The Xfinity store told me to cancel my service (Losing the $45.00 they just took out of my checking account March 1st) then they could help me set up a new account.  Of course they will charge me $25.00 for the modem and $40.00 for the service, stating this is the only thing they can do.  I'm considering cancelling and finding another carrier.  What should I do?