Totally agree with you Mike, customers do tell porkies like that... they think people are stupid and will just drop their price in reaction the the fictional "other quote".
Truth is all of us are stupid some of the time, and some of us are stupid all of the time

But whenever I've been in this situation and asked to see the written quote, guess what? Nothing materialises

Phone quotes are not quotes, they are estimates from the information given, and how many times have we turned up to clean a "12x12" lounge that is actually an 18x14 lounge?!!
However I too have noticed the local CD franchises are quoting much less than before, when I've actually had a conversation based on the truth with trustworthy customers - the ones who've chosen me to do the work but still tell me the other estimates they've had. No need for them to lie at that stage so no real evidence needed.