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If you havn't mentioned their company name in it you could say that one of the sites below your listing asked for this proposal and chose not to take you on. now you rank way above their site and just for a one page proposal, so if you had a site to work with, where could that take it, sort of thing.
Did you try to get the business back when you spoke to them?
Can you leave it on there and sell them some leads or sales?
And, we have all done this. One of the best hires I ever made what my second choice when my first choice changed her mind about taking the job.