My girlfriends sister filled her 8 month old fiesta up at a garage and since that it started cutting out.

Towed the car to a mechanics last night and told this morning when he took the fuel filter off the petrol is comtaiminated and brown

He is going to give me a sample and also all fuel from tank.

Does the garage she bought it from have to pay for all the repair costs to the car?

Im hoping it hasnt damaged the injectors as she drove it for about 8 miles

Is best thing i can do it go to the garage with the sample or is there anything else i can do?