Stop driving, document everything before anyone touches the vehicle, and notify the repair shop of the defect in writing immediately. Under Swiss contract-for-work rules you can claim rectification and compensation for the consequential damage — but late notice can cost you those rights.

Why the first days decide the case

A vehicle repair is a contract for work under Swiss law: the shop does not just owe an effort, it owes a result — a repair that is free of defects. If defective work later damages the engine, the gearbox or anything else, the shop is in principle liable both for fixing the defect and for the consequential damage it caused.

In practice, these cases are won or lost on two things that happen long before any lawyer is involved: whether the defect was notified in time, and whether the causal chain can still be proven afterwards. Swiss law expects you to examine the work and give notice of defects promptly once they show themselves. Waiting weeks while the problem gets worse weakens both your legal position and your evidence.

Secure the evidence before the next repair

The single most common mistake is having the damage repaired — by the same shop or a new one — before anyone has documented its cause. Once the parts are replaced and discarded, proving that the first shop's work caused the damage becomes very hard.

• Photograph and film the damage and the surrounding parts before anything is dismantled.
• Keep the invoice and order description of the original repair; they define what the shop owed.
• Ask the second garage to record its findings in writing and to preserve the replaced parts.
• For significant damage, consider a neutral expert assessment before repairs; in a later dispute, a jointly appointed or court-appointed expert carries far more weight than each side's own mechanic.

Notify the shop in writing — precisely

Send the shop a written notice, promptly, describing the defect and the damage, stating that you hold it responsible, and inviting it to inspect the vehicle. Precision matters more than legal vocabulary: what was ordered, what failed, what it caused. Give a short deadline for the shop to respond and state that you will otherwise have the damage assessed and repaired elsewhere at its cost.

Do not let the shop's insurer or the shop itself dismantle the evidence unilaterally: offer inspection, but on documented terms.

What you can claim

If the defective work is established, Swiss law gives you a choice between rectification by the shop, a price reduction, or — for serious defects — rescission, plus damages for the consequential harm the defective work caused, such as the follow-on damage to other components, towing or a replacement vehicle. If trust is gone, you are generally not forced to let the same shop try again where rectification by a third party is justified — but that step should be taken after notice, not instead of it.

Every case turns on its record: the order, the invoices, the notice and the expert findings. If the damage is substantial, it is worth discussing your specific situation with a lawyer before the next repair is commissioned.