Decking subframe

I have an issue with a contractor who has built a timber subframe for our decking. Having reviewed the work I noticed joists were not flat. To test this I placed spirit levels and newly bought pieces of 2x4 perpendicular to the joists. I measured this in three different places, and there were gaps from 4mm to 8mm. I have included pictures showing the issue and to illustrate the point to him I used coins. I have included a sketch I did showing the joists, the reference tools (a piece of 2x4 and a spirit level) and the gap to the joist in each location.

I've also included a video showing how much a piece of 2x2 rocks on the joists.

I am worried that a) it will cause water to pool b) furniture, chairs and table etc when placed on the decking will rock and c) I believe the gaps shouldn't be there.

The reason for the query is the contractor is telling me that there's no issue, the frame is solid and that he isn't going to fix it.



Any thoughts welcome
Thanks

 

He got the level wrong so the turf would have come too high up the side of the decking, so to increase the decking height they screwed 2x2s on top of the existing 4x2s. To make life easy, my solution to him was to unscrew the 2x2s, place shims at 200m intervals along the 4x2, then screw the 2x2 back down.

I don't want a decking with bows and dips etc in it. I feel like this should be fixed?