I had my 1.2 16v dynamique serviced at 18k at my dads mates VAT registered garage only cost £60 inc parts, reno wanted £140, my car has been in a few times for different warranty work since then.....its now on 22,300 and having the throttle body replaced this week under warranty and no one has mentioned anything about servicing at renault, i've got exactly 12 months of warranty left on mine.
To be honest Shaun if you get it serviced at a garage you trust more than reno all you have to do is make sure they use genuine reno parts and they can't refuse you warranty work, you can actually buy a service kit from reno, oil filter, sump plug washer, 5W40 fully synthetic oil (elf excellium) as recommended by reno, air filter, polen filter and whatever else the 182 requires for its 36k they'll sell over the counter to you at your local dealership parts department.
Hope this helps, Alan.