Am I wrong in this handyman situation?

We hired someone to sand the very old wooden floor in our new apartment. It is very hard work (old paint and glue had to be scraped off with heavy machines) but he said he would be done within the week and he gave us what we felt was a good deal.

Two days in, he suddenly said he’d passed the job on to his sons (16 and 20) because the fine dust was messing up his already weak lungs. He didn’t mention this before – if I’d known about the lung issues, I would have found somebody else to do it. Two more days in, we realized that the sons never start work until the afternoon. Then we discovered that the finest grain they were using was 100, which means that the floor didn’t feel or look actually finished – even though they declared it so.

It is now eight days after work started, and nobody showed up today. I asked why, and was told I needed to understand they are “humans, not machines”. The floor is finished to 100 grain in two of the three rooms, but there are visible scratches from the sanding machine all over. As the machine is round, the corners are still covered in glue and paint in all rooms. Room number three has been sanded only in the middle. Every day, I’m told that they’ll be finished “tomorrow”.

I’m pretty annoyed, but at the same time I feel really bad for those people. The sons are basically doing ten-hour workdays – they have school and work in the mornings. The dad suffers from COPD. They don’t have a lot of money. Obviously, they didn’t realize how much work this project would be, and I feel like we’re taking advantage of them. We paid a fair price for five or six days of work, but for one person. We certainly didn’t pay enough for three people.