Get the service done at your mates place and then take it to ford for your paintwork warranty check.
As long as you have receipts for the work done your warranty will be fine, my first service was at a vauxhall dealers and then took it to ford for the paintwork check. Its just had its 3rd year service and i spoke to my warranty guy as the car has only done 900 miles since the last service due to having 3 cars, the car only has about 12,900 miles on the clock, he said it only needed an oil change and paintwork check, i supplied the parts cos i got them trade and ford did it for £25 inc paintwork check, nice one.
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Fiesta ST200, K&N Panel Filter otherwise standard for now.