At a body shop they can use whats call a spoon.It is a thin piece of metal tool that fits between the front fender and door gap.Then depending which way pulled moves the fender in or out.This is done when putting on when new fenders are doors to get the two to alighn perfect,Since your is already finished you have to be careful doing the not to chip or put dent in fender.That probly why shop did not want to try.You could use a plastic trim tool the same way and be alittle safer but there is a chance of rolling fender edge or dent then its mud and paint time.But if your set on new fender worth a try.