Advice for poorly layed patio?

We got a builder in to re-do and add to our current patio. He didn't dig down far enough, didn't appropriately level out the earth and then didn't put hard core across the entire space. Only in the areas that he though needed raising to meet certain levels of the earth. Slabs went down. Levels were completely out, we asked so some to be lifted and re-done as they were concave to look at. Even after they were not level, some where sitting too high. Visible to the naked eye. We got fed up with the disorganisation and stopped the work. Decided to get another builder to look at what had been done. He pointed out that it had not been dug anywhere deep enough to give a stable enough based to work from. He showed us what he was talking about. He started to lift the slabs by hand without any effort , only one broke out of the 96 layed. They weren't even held down by the cement. Pointing broke away and crumbled. We contacted to original builder and said that we weren't happy and would like the labour cost back that we had paid in good faith. The original builder is employed by a salaried job but was turning up in the company vehicle in the evenings to this work. We asked whether our patio was being done as a self employed job or under the name of his employer and he didn't like it. He agreed over the phone (we have a recording of the call), to pay us the labour cost back. He's now asking for photos of the space having been dug up again because he's adamant what he did was accurate. Has anyone got any advise please. Many thanks