Do I get a guarantee on car repair?

If my insurance company recommends a certain repair shop do I have a choice?

The insurance company cannot require that your vehicle be repaired at a specific repair shop. However, an insurance company can recommend that the damage be estimated and repaired at a specific repair shop. The insurance company often has "preferred" repair shops that they have set up. These shops have agreed upon certain terms with the insurance company.

Is there any guarantee?

When an insurance company states or implies that they guarantee repairs if you take your vehicle to a shop they choose ask about the details of that guarantee and ask to see the written guarantee. It can be that an insurance company’s guarantee is actually the shop’s guarantee, and the responsibility for a satisfactory repair job will remain a contractual matter between you and the shop – just as if you had chosen the shop.