I’m a contractor in hilton head, we did a paint job for fence and gates for a gated community, gave them 2 prices they went with the cheaper one. The price was $15,500 to do entire fence and $9,500 for parts you can see from road. They went with cheaper one, then they changed head of board after we finished and he wanted it all done, we did it then they didn’t pay anymore and still only wrote a check for 9k, so we did extra work and got paid less than original. And they were late on that and my invoice says after work complete there is a 10% late fee after 30 days of completion daily. Never had to do this before so need advice. Thanks