modem service!!!

Evil Cox just lost me. AT and T called and in my OS zip is a new
wireless service for $12 a month less than Cox and $30 for a modem
{that means I send in a rebate to get it down to $30} and a $200 set
up fee that maybe you could do for me. My question right now is
this, there is a modem downstairs. How can I or they know that it
could be used instead of my buying a new one? Apparently that modem
or the spaceship thing is weak or broken or is breaking because after
3 men helped me and many calls to Cox, I still cannot use my wirelss
in the piano room. In the guest bedroom it is perfect, in my bedroom
it is weaker but OK, in the piano room it is dead. Do you see what I
mean? But maybe the problem is the spaceship. Or maybe it is
COX!!! I want to go ahead and order the AT and T deal but if they
come out to see if the modem will be OK for their service, they will
charge me $200!