Could be the water pump? - People often skimp on this to save money during a belt change, but it's false economy as it's run off the cam belt, so if it goes it's the same labour again to have it changed!
Agree with montana, if there is no invoice of the work being done then take it as given that it's not been done, regardless of what you were told when you bought the car.
I've just had job lot changed on mine. Cambelt kit, aux belt kit, water pump and de-phaser pulley. Even though it's ticked in the book as being done and wasn't due until another 3 years there was no invoice to prove what had exactly been done. At least I know it's going to be sound now for the next 5 years. Not worth the risk for what it costs. All the above I got changed for under £500, so not too bad. Some places will try charge £600-£700 but it really shouldn't cost that much. It's quite a labour intensive job, about 4-5 hours normally and it's a bit of a pig to do. Just make sure you take it to someone who knows these engines and has the correct timing tools to do the job if you decide to go for the full change.
Where are you based? ALS-Performance up in Cumbria did mine for £460 all in and they even supply the full kit
here all genuine Renault parts and Renault timing tools used. Would highly recommend them if it's not too far.
Mines as quiet as a mouse now and nice and smooth, before the change there was defiantly some sort of bearing noise which I'm guessing was the water pump and it didn't sound too great, whined a bit if you get me on acceleration at the low revs.