A service is known work, so it is a price. Oil, filter, plug, a fixed list of checks and a fixed hour. The form says three hundred and twenty and the receipt says three hundred and twenty.
A repair on a six year old bike in this air cannot be priced before it is stripped, and anybody who does it anyway is quietly pricing in the bad days. A bolt can shear while it is being undone. A bracket can come apart in somebody's hand. A caliper slide can be seized solid. None of that is visible from the outside.
So a repair booking buys the strip and the look, and then you get the figure. Nothing is fitted before you agree to it.
And when a job grows we stop and ring you. Every time, whatever the size, even when it is forty rufiyaa, and this is the part that surprises people. The reason is simple: a customer who gets rung about forty rufiyaa never spends a second wondering whether they would have been rung about four hundred.