We had the same thing, water was fine but car apparently overheating. It needed a new fan as the other was unable to move, apparently it's a problem with the design of the car (the fan is right at the front so get's knocked with stones, and first point of contact for all weather). Cost us about £180 :'( to get a new one and fitted and have since found out the relay wasn't working too so even with the new fan it couldn't actually go around. I'm not happy that the relay wasn't checked first, it may have saved us spending so much on the fan so perhaps ask them to check the relay, if that's ok you may need a new fan.
Mulli
July 2009
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.