Since it rained, WD40 probably won't hurt since it displaces moisture.
What I got from other websites:
When necessary, apply a thin film of Spray White Lubricant or equivalent, directly to key. Insert key into lock and actuate several times. Wipe excess lubricant from key.
Particular attention should be given to external lock cylinders during fall and winter months to insure protection from water and ice."
"Doubt whether anything is broken and needing replacing. Have had a similar recurring problem with my '60. It has been in the family since new. Have always been able to correct the "dry lock" problem by freeing up with liberal application of WD-40 to the entire mechanism and then shooting in some spray lith-grease for longer lasting lube effect. I remember the panic I felt the first time my door would not close, about twenty years ago, on the passenger side. Since then, all three of the seldom used doors have presented the problem at one time or another. Each responded well to the treatment recommended above and without having to remove a door panel. Just clean up any over-spray so it does not collect dirt"
I would take it back to the guy and request the fixes. If he doesn't fix it, file a complaint with the Better Business Bureau and the State License Board. You can find out his business license number and official business name by calling City Hall. You can point out this as an alternative to not fixing your car. Just don't take your car back to the guy. If you have to pay someone else to fix his work, keep the reciepts, send him a letter and a copy of the receipsta and request reimbursement. If he doesn't send you any money, file a small claim case against him.
In the future, never leave your car for two weeks with anyone. They are incompetent business people who don't car about their clients. Why put up with nonsense like that?
PS: Just my .02.
You have to decide the best alternative for yourself.
2004 E60 530is, Delivered 12/12/03, TiSilver/LGrey, PP, SP,PS, PDC, ACC, FRS, Step, Xenons, clear bra, body colored rear inserts. (Retired, 1983 henna red 320is)
2004 Corvette Z06 Commemorative Edition