What is the name of the garage, so the rest of us can avoid them!!
If they are in recievership, rather than simply shut down, you may still have legal rights.
Have a look at your house and car insurance policies, many now include free personal legal assistance.
If you are a member of "Which" magazine they may be able to help. Have a word with trading standards too, as the garage have clearly been incompetent.
Afraid I cant give any practical advice on the gearbox, try
www.renaultforums.co.uk
higs
August 2009