Hi Phyllis, I think Greensmith is commenting on how your setup seems to have lawsuit written all over it - it wasn't a personal attack. Please bear in mind that this site was originally built for landscape contractors.
Now, to the question at hand - at first I thought you'd said the patio was built six years ago, and I was thinking - sheez, it looks like only one paver moved in six years, that's pretty good performance.
But six days is something different.
I'm not a fan of Envirobond sand for the very reason you are witnessing - when it's thoroughly wet, it's about as soft as beach sand. When it dries, it dries up hard, but often times there are weed seeds sitting in those joints, and when that water gets in and softens that sand, those seeds germinate and grow. This would also apply to any other sand with an organic binder.
I don't know anything about your contractor and their experience with organic and synthetic binder sands, so I'll say this: when I first installed a project with Enivrobond sand, I was led to beleive that once it got hard, it stayed hard, and the softening during subsequent rains was minimal. I confidently said the same thing to the client, and later had quite a bit of egg on my face when they had more grass growing between their pavers than they did in their lawn. I was very embarrassed and angry, and that experience has affected my product choice, as one might expect.
Your contractor may be in the same boat, and have little experience with sands using organic binders, and may not be aware that washout can be a real issue with that sand. So I'm not here to pass judgement on whether what your contractor did was right or not.
From the picture you posted, I can only see a single paver that appears to be sitting below the rest - that issue may be more pervasive than that, but that's all I can see. With that, I'm left to wonder if the paver (or pavers) themselves weren't made within ideal specs - we use one mfg in my market sparingly because their pavers and block can vary +/- 1/8". Put one from each end of the spectrum next to each other and you have a 1/4" difference. That's pretty big and noticeable. Without being there to see the project, it would be very difficult to be sure if that was the case or not.
But no matter what, I believe you have 2 separate issues here, one concerning the different elevations of different pavers (caused either by variations in paver thickness or inadequate base prep), and one concerning the joint sand. Washing out of joint sand would not cause pavers to settle. If the rains were torrential for three solid days and the base prep included a course of bedding sand, then maybe. But it's very unlikely.
To fix the joint sand washout issue, my recommendation would be to wash out the organic binder sand, allow everything to dry completely, then install polymeric sand.
Hope that helps.
This discussion has been included in the site beginner's polymeric sand page. 
