How should I deal with my boss this morning?

I work as a tennis coach for this man, but last week he reeled us in to paint the clubhouse. There were 3 of us working on it on the Monday but then they got fed up and I ended up finishing it by myself. Overall, I put 28-30 hours in on painting alone, then I did 3x3 and 1x2 hours of tennis coaching. So that's about 40 hours I did last week... My boss is avoiding the issue of payment and went away at the weekend, leaving a subordinate to give me only �50. If he thinks that is enough for all of the work I've put in he's got another thing coming. I get paid cash in hand from this douche. How do you think I should go about getting the money out of him this morning?