I know you're broke down and at their mercy, but if they couldn't get it started, how did they diagnose all six injectors are bad. If they had a code stating all six were bad, different story. I think you'll find they'll do all this work and the coach still won't run. The bill will start growing astronomically.
I would want some proof that there is no fuel at the injectors. At least have them walk you through their thought process and why they feel you need all of this work. Put a little pressure on them to assure you they're not just shot gunning this issue with parts. Sometimes a little pressure will make them rethink spending your money.
Good luck....
