The only likely answer lies with either your car insurance (when the engine blew you could have an option that allows a replacement car) or the garages insurance. You need to talk to them about that. You may even be able to sue them for the lost income and again their insurance would cover that. If you have a credit card they sometimes come with free legal advice (Barclaycard was one) give them a call or if you have home insurance you could get free legal advice as well.