Your basically transplanting a crape myrtle from one location to another. Buy the correct color Crape myrtle this time and plant it where the wrong colored one was planted. Move the Pink colored one where he wants it. Only guarantee the new White Crape myrtle for 30 days. After that it is up to him and nature. The pink Crape Myrtle would have no guarantee and as far as the Azalea is concerned you are not responsible for that plant at all. I would not charge this customer for the White Crape Myrtle or your labor. If he does not except your offer, thank him and walk away. If he excepts your generous offer per my suggestion do the job, move forward.