Main dealers always charge loads, def worth shopping around, your book doesnt need to be stamped by a renault main dealer if you went to a specialist im sure that would be just as good.
Nissan tried to charge my mum 300 quid to fit 2 cv boots on her almera, we went and got the parts for 40 quid and paid a private garage 60 quid to fit them, i really dont know how main dealers get away with it.