Most of these companies are associated with the insurance companies, effecting repairs after fires, water damage from plumbing failures and the other myriad of disasters that can strike a home or business owner. If you had gone through your insurance, the companies oks the repairs and foots the bill. The home/business owner can push for further work, if what has been costed out hasn't covered all damage that they say was done.
You sound like you hired them yourself. I don't know the extent of the damage, so I don't know what was agreed upon. From the sounds of it you hired them to do a general clean-up and dry the affected areas. After this was done, the dame can be spotted, but again, I have not seen what the issue is and what was agreed upon.
Any company will harass someone who doesn't pay their bill. They can also put a lien on your house, even for a paltry sum, but I don't believe small companies can affect your credit rating, but they can send this unpaid bill to a collections agency, selling this debt to them and they will harass you more.