year 2004 plate
Welcome to Fluther.
You might enjoy this site very much, except it doesn’t list Vauxhall as a make. Perhaps there’s something similar in your part of the world?
Try this website onVauxhall Meriva heating issues.
Looks like £600 is tops.
£600 is a ridiculous cost, if its a 16V model you can do it yourself for around £40 all in..we did it today and documented the whole thing here..
http://www.ultracars.co.uk/vauxhall-meriva-thermostat-replacement/