Dealership modifying engine faults to hide liability

[Danielle287]

Hi, recently our car engine failed. We had it towed to a garage who said we should try get the dealership/actual brand to take responsibility and fix it as the type of problem should not have happened on a fully serviced car with 40,000 miles. They decided they wouldn't give any goodwill after a 3 week investigation so we had it towed back to our local garage to have it fixed cheaper. When it's gone back to the first garage the mechanic has said the oil filter pump had 4 cracks in and the dealership have modified it to try and hide their liability. Anyone know what sort of avenue I can go down?