Hopefully i can help..
What year / model / engine is the renault you have?
Did the steering feel heavy at all prior or during fault?
Any warning lights etc?
Hi..there thanks for your reply..
Ok..You dont say what model or Renault you have..but as far as the steering system stopping the car from starting..i cant see it - power steering shouldnt really cause the engine to not start - if your steering is hydraulic via a pump on the belt side then again shouldnt stop the car from starting..It sounds like either they have wired the leads up wrong/wrong coil pack or something else has been disconnected and not refitted back..does the immobiliser turn off if not then the problem maybe due to that...have they ensured the timing belt is still intact / have they checked fuses,main fuses/relays.if the car was running correctly before it went into their hands then they have obviously done something wrong to allow the engine not to run..I do hope this helps