Write to the dealer principal of the supplying dealer telling him that the engine of your car had failed just three years and five weeks since you bought it, despite always having been maintained by Ford dealers on time. State that under case law on the various Sale of Goods Acts you have a "reasonable expectation" of six years life from an expensive consumer durable such as a car and for it to have failed after just three years and five weeks it must have been sub-standard. State that if the dealer requires payment to strip down and repair the engine you will pay for this, but you will then avail yourself of the Small Claims Track of the County Court to seek a full refund of these costs. Send this letter by Post Office Special Delivery, keep a copy and staple the certificate of posting to the copy so it becomes a matter of record for the court. Details of how to make a Small Claim here: www.gov.uk/make-court-claim-for-money

Details of the law that applies here: www.honestjohn.co.uk/faq/consumer-rights/