Get the pre approval in writing. We're going through this at the moment, made the mistake of only getting verbal pre approval, lender told us to go and make our offer, we found another block $60,000 less than thought we'd borrow and lender has since said she can't help us. We've now been jumping through hoops for weeks and we're still no closer to getting the loan.

Getting it in writing would have saved us the heartbreak.