my car engine blew up

I got my car fixed at my local garage after the fan belt went - they also had to fit a new part. Next day driving to work there was a terrible noise and the engine just about blew up. Apparently this part was either fitted wrongly, or was itself faulty. Now the garage is refusing to fix it as they say it was the part not them. Its been with them 4 weeks whilst they argue with the part supplier who is arguing with the manufacturer. The garage refuses to accept they should fix my car until they re reimbursed by either the supplier or manufacturer. I feel helpless. I really dont want the expense of taking them to court and I need my car now to get me to work. Its costing me a fortune in car hire. What can I do?