I remember the first cars I had, which could be unlocked only with the key. Back then I always used a lighter to heat the key and then used it to melt the ice in the lock.
My wife has such a problem with her Beetle - the side windows have no doorframe and when you unlock the car these windows roll down an inch, but sometimes they are frozen and she cannot open the doors - she has wanted a fancy car, and now she has to wait outside sometimes ;)
!DERANGED
!BEER