worst part of running your own business is chasing people down for money.
A person who doesn't pay is not a good customer.
And you are not the first person they have screwed over, letting them complain to their friends just keeps more of those losers away from your business.
My favorite was when you called and called and they finally went "oh, it went out weeks ago, can you wait one more day?" (ok, it's always possible the USPS does lose stuff)
and the next day the check shows up
postmarked yesterday
lying fuckers
reason #856 this country is doomed. (fuckers who don't pay for work)