Assuming that you don't get anywhere by simply demanding to see the boss and demanding compensation, here's what you need to do.
Step 1:
Find out EXACTLY what it's going to cost to get the problem fixed. (Either get a written quote or get the work done and retain a copy of the bill).
Step 2:
Send a formal letter to the tyre company. If it's a limited company it should be sent to their registered office. You can find the address here:
http://wck2.companies...ame=accessCompanyInfo
Assuming that it's a limited company, your letter should be addressed 'To the Company Secretary', not to any named individual. Your letter must be dated and show both your name and address and that of the company you're sending it to. It must clearly state that it's a demand for payment, specifying the amount and the reason why it's due. It should also clearly state that if payment isn't received within a defined period of time (I suggest 14 days) you will commence legal proceedings to recover the money owed to you. Keep a copy of the letter and send it by recorded delivery, retaining the proof of posting.
Step 3:
If you don't receive payment, commence a 'small claims' action using HM Courts Service's online system, here:
https://www.moneyclaim.gov.uk/web/mcol/welcome
Chris