Hold on everyone...

You can argue that he didn't need all those chemicals and I would agree (in fact I'd like to know where the leftover chemicals are). But the PB is running a business. If you're going to hire someone to go to the store for you then you are going to pay more for it. Yes, those prices are high, but not when you consider that they're delivered to your doorstep and put into your pool for you.

Next year let them open the pool for a set pre-negotiated price and then handle the water balancing on your own.