Shop around your local independent garages for a price.
Quality kit including water pump and tensioners should be about £250 for the parts.
£650 all in, is a bit on the nippy side!
------------- I came into this world with nothing and I've still got most of it left.
Depends on who is doing it, , the price is about right for a Fiat main beater garage.
Had mine done at a main dealer about 6 years ago and it was about £625 including tensioner, belts, water pump etc.
If you can find a garage that has good recommendations that would be cheaper.
Whoever does it make sure you get the water pump done at the same time