2008 C70 T5 M66. 2 remote keys. 1 works flawlessly. The other key? Not so much.

About a month ago - wife's remote wouldn't allow keyless entry (have to push unlock button on remote) or keyless drive (have to pull out the stove knob and insert key into the ignition to start/drive car).

Replaced remote battery...didn't fix the issue. Took it in to dealer - was told that "it's either the key or the car's Keyless Drive/Entry system..would be $125/hour to diagnose, plus cost of fix. If new key is needed (key cannot be reflashed or reprogrammed)...that'll be $250 for the key and another $65 to program it. if it's the keyless entry/drive system...who knows?'

All keyless functions work on one key, but not the other...so that eliminates the keyless entry/drive system, correct? Any assistance or advice would be greatly appreciated.

Remote functions work on both keys...so thinking both keys are programmed/recognized by the car.

That leaves keyless transmitter or RFID 'tag' in Mrs. T's key, right? Any ideas on how this can be checked or fixed without shelling out over $300 for a new key and programming?

For now, Mrs. T borrows my key...or pushies buttons on her remote, removes stove knob and inserts her key to (seldom) drive Tomkat.