Depends precisely what you mean.
For example, I don't think there's anything illegal about me calling myself Anstruther Taxis, Crail Taxis, Elie Taxis, St Monans Taxis and Pitenweem Taxis, and handing out cards or leaflets or advertising in each village with names specific to that village, but with the same phone number, say.
Or using individual internet domain names for each village, eg
http://www.elietaxis.co.uk,
http://www.pittenweemtaxis.co.uk. Even though I live a few miles from any of them.
But if I made specific factual claims that were incorrect then that would be a different matter. For example, if I stated that I had cars based in each village, or had an office in each village, or that I could respond to a call in five minutes. If none of that is true then that could amount to some sort of false advertising.
So unless it's the latter kind of thing then I doubt it's specifically illegal, but if specific false claims are being made then maybe trading standards would be interested.