Garage Bill Is Too Much
Estimates, quotes and contracts
If a firm price is stated at the time of making the contract, then both you and the garage are bound by it. However, you should establish whether you have been given a firm quote or, as is more usual, an estimate of the price. Generally speaking, an estimate will not bind the garage, although it will be an indication of the eventual cost.
If no price is quoted, the garage can charge you a 'reasonable' price for all work properly performed. What is reasonable is a question of fact, and a court would decide the question by reference to the work done, market rates, and any previous dealings.
Note: A price will not automatically be considered unreasonable purely because other garages in the area charge less.
The garage has done work I didn't ask for