Originally Posted by
akl_traveller
Should is correct; If you have a copy of Fowler's Modern English Usage look at "shall and will" (page 548 in my copy). You are correct that there may be even more pleasant ways of phrasing it, however e.g "Is it possible that you might have..."
If you look at the actual modern usage of the word "should", you will find that most people find impolite
"Should" means "ought to", "supposed to", ... Like you are telling someone what to do, as if they were a little kid.
Now, if you used "shall" it would just go over most people's head.