Not to sound rude but First thing reread your post title and use the correct words makes no sense to most people but I get your trying to say 120k mile service. Second no one knows if you got ripped off if you never put a price of what it cost or what was done to it might want to edit that in there. Thirdly your paying for preventative maintenance at 120k miles and not knowing how to it is the price you pay for service and the convenience of someone else doing it whom also have the correct tools and knowledge to do it in a timely manner. Also preventative might save you money in the future to where your not stuck on the side of the road getting your vehicle towed because you didn't want to pay for the service and parts

Me as mechanic I don't know how create a web design page but I could learn over time but I much rather pay someone else who knows what they are doing.