Honestly dont worry about it.
If anything its good for your business, the numpty who is doing this wont last forever, and your cheap skate custies who went over to him, well that shows how much they value your service, and who wants customers like that anyway?
And even if he does make it a success, he will at some point have to raise the prices, or start cleaning more frequently to compensate and then he will be back to square one again when they start dropping off like flys.
And then of course if he is so cheap, then its likely to be someone who doesn't pay tax, and isnt insured.
About 6 years ago there was a company not far from me who were trying on the same game, they lasted 2 years, south African bunch