Your Insurer may tell you that you have to use their own Approved Repairer, this is not the case!
You have the right to use the Repairer of your choice. Your Insurer may advise you to use their own Approved Repairer, but the final choice remains with you, the Policyholder. All Insurers have an obligation governed by the FSA to “Treat customers fairly”.
It is best you know ‘who’ and ‘where’ your vehicle is going to.