Yeah @stefano, that shit really sucks, but we all come out wiser afterwards. Now, we sign NDAs, set up parallel and independent communication channels for the project, request all the paperwork, including invoices and active contracts, and have their legal department review everything again, while also giving a copy to ours.
If you're lucky, you'll catch that greedy company breaking its own terms and conditions, because nothing says *professional* like screwing themselves over and accidentally making your migration a bit easier.