Do garages try to sell unnecessary extras when you go for a service?

I recently took my 2015 Ford Fiesta auto (12,000 miles) for its three-year service at our local Ford dealer. We had agreed a price for the service and MoT, but they asked if I wanted to pay £25 more so they could flush the old oil out properly. They said they recommend that so I went for it, but surely emptying out the old oil should be part of the service. When the car was on the ramp they phoned and asked if I wanted the aircon regassed (£69) and whether I wanted the fuel system flushed out (£40). I declined both. Were they trying to sell me things I didn't need? If it was needed, surely it should be included in the fixed price. I feel as though I was taken for a mug by these 'extras' being offered so late in the process. What do you think?
Oil flush is added to the old oil before draining to help get rid of contaminants, but if used it is crucial that the oil is drained from the sump plug, not siphoned out, otherwise residual oil flush will contaminate the new oil. If the oil is changed every year it should not need an added oil flush. If the car is run on Super, that contains all the additives the engine fuel system needs, so the fuel system should not need a flush. A/C loses refrigerant all the time, but if it is run every couple of weeks through the winter, that keeps the lubricants circulating and helps prevent leaks. Might need a regas next year.
Answered by Honest John on

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