If you are acting as a consumer when you buy something either goods or services you enjoy certain ‘statutory rights’ that you don’t as a business. If something does go wrong with the purchase, the first thing to do is to talk to the provider as this may resolve the issue. If this doesn’t work then writing to the owner of the business is the next step. If the garage belongs to a trader scheme such as Motor Codes or Buy with Confidence these organisations may be able to help. However if all else fails you may have to resort to the Small Claims Court.
Helpful consumer advice can be found on the Citizens Advice website or the Which website along with template letters and other useful guidance.