If it were a faceless corporation, then I'd certainly do as otherts suggest and allow the bill to go unpaid due to their incompetence or whatever.
But a local family company could be seen as a different matter.
Essentially it is, as you suggest, down to conscience, but (i speak only for myself here - this is not advice or judgment on you) , I'd make sure it was paid.
Small businesses have enough to struggle with, without having people fail to pay for the goods they buy. I'm sure the company is not right on the edge, but if they were and went belly-up because of a series of unpaid bills like this - I'd never be able to forgive myself for being a part of that.