As far as I know, it is part of the radio for all 96-98 EXs, so if that is the problem you would need a new radio. Make sure it is an 96-98 EX radio because the other ones don't have the key less entry I think. You can tell because you can see the antenna on the back if it is the right one. I don't know if you need a specific radio because you have an alarm or not. Mine doesn't have an alarm, it just has the keyless entry. You can probably find one for cheap used. I don't know how you can tell for sure if it is actually the radio or it is just the remote. You can at least try the first 3 steps below to see if the valet button unlocks the doors without the remote, that might not help you much though. If Honda checked another remote, maybe they are right? Hope this helps a little.Here is how you program a new remote. If you buy a new radio you'll need to do this.

I think you have to close and lock the doors before hand for it to work, but I could be wrong.
1) Turn Ignition to On, but do not crank car
2) Within 10 seconds, press and hold the valet button (Slim button b/w the AM-FM and CD-Tape buttons)
3) While holding valet button, listen for the door actuators to activate
4) Continue holding the valet button and press a button on your remote
5) Still holding valet button, lister for actuators to activate again
6) While holding the valet button, turn the key all the way back (off)
8) When the car is turned completely off the radio may flash (the screen would have been blank the whole time)
7) Remove key and test remote

REMEMBER: You cant let go of the valet button at all during the process.