BMW Repair: Electornic Locks, antenna amplifier, vehicle locks

Question
I have a 2000 328i --- when the weather is warm (hot) the remote key will not unlock the car and I have to do so manually -- in fact the master unlock also will not unlock leaving the drivers door as the only entry and exit.  The dealer has suggested replacing each lock on each door but that seems a bit odd since the master won't work --- my guess is the hot weather is expanding some metal causing a short.  Any thoughts would be appreciated.

Answer
Philip, Does this only happen with one of the master keys or both of them? Try replacing the battery in key. Re-initialize both keys(turn key on, then off, remove hold unlock and press lock button 3 times then release unlock button. 2nd key hold unlock and press lock three times, then release unlock) Vehicle Locks will move if successful. Try swapping the Antenna/Amplifier for the remote with another. You have some options to try.
-Evan