I think £25 is a reasonable price to take a door off , trim a bit from the bottom and refit it. I t must have been at least an hours work and there is more to an hourly rate than just the workmans pay. the cost of a van insurance etc, tools and other commitments have to be averaged over every hour he works.
I think we often have an unrealistic idea about how much a job costs.
We are having an extension built. DH is the designer, project manager and is doing parts himself. But looking at the bills we have coming in from our good reliable builder, who we have been using for 25 years, and the other craftsmen, it is clear that many people really have no idea how much an hourly rate is taking in any workman's overheads as well as pay. Workmen are entitled to a good wage for the exercise of their skill and training. We use them to do work we cannot do.
I have just painted the whole of the outside walls of our extension to save money. With paint and materials it took the equivalent of a full working week, and I am quite a fast worker. We had a quote of just over £1,000 to have it done for us - and that did not strike us as unreasonable.