Danger Will Robinson Danger!
Having had the 'fun' of doing a head gasket, water pump, full belt change, clutch, CV joint(s), wheel bearing(s), coil packs and sorting the dodgy earthing on it's larger - less fun - french brother the Meganne it's not the sort of thing you want to take a chance on. To add to my anti Renault stance the current better half had a blue 182 and the loom was basically fried within a matter of weeks outside the 3 year warranty, Renault didn't want to know and only the fact she knew the family who owned the dealership chain perosnally got it sorted withiout having to go legal. They are a lovely car to drive but certainly not one you want to take any chances with when it comes to service work or history.
Call the places that did the services yourslef, the delaer telling you he did and it's all OK is worthless to you in the event of it going you can't prove anything and at best they'll just point to the people who did the service and say 'they told us it had been done'. If you can't get written confirmation in the form of a copy invoice or job sheet then it wasn't done. Getting it checked is pretty pointless as a cam belt can look OK and still go with little or no warning, it's not always going to show signs of wear round the edges or show signs of cracking, have a look at the renault forums and you'll see what an utter PITA it can be and why people feel so strongly about this issue.
So either they prove it was done, do it themselves in with the price (you shouldn't pay) or they drop the price by a significant enough margin that you can comfortably budget to have it done elswhere by a good renault inde.
To put this in context you're talking about a manufacturer who seems to go out the extra mile to make jobs harder and more expensive. For example with approx 3-5cm extra clearance a clutch change on a Meganne would be a lot cheaper as you wouldn't have to remove the lump to fit the clutch, think you can leave it in situ and raise the body/drop the chassis as that'll be quicker ? Nope they thought of that and made it equally hard. They're also happy to ignore various bonnet catch/coil pack/exhaust manifold issues and locate fuse box's directly under scuttle trays sealed with cheap foam and drain holes that an ant would struggle to pee down and then try and charge the earth to diagnose the problem and don't even get me started on the connection for the starter motor being in the worst possible place and almost totally unprotected.