Warranty claim enforced: commitment within two days

The smart lock was rattling; according to forums the manufacturer's support takes ten days. The AI ruled out software causes, clarified the legal position — replacement delivery under § 439 of the German Civil Code, burden of proof on the retailer in the first year — and pulled the invoice from the document archive. The letter to the retailer went out with a deadline; two days later its managing director committed to the replacement without reservation. The manufacturer ticket ran in parallel, but handled so it would not undermine the stronger claim. The refund still took four weeks to arrive — the follow-up with proof of delivery was again written by the AI.

Me: “The door lock is rattling — what are my rights?”

1. Rule out software causes, document the defect (video, log).
2. Clarify the legal position: replacement delivery under German Civil Code § 439, burden of proof on the retailer in the first year.
3. Pull the invoice from my own document archive and draft the letter to the retailer with a deadline.
4. Run the manufacturer ticket in parallel so it does not undermine the stronger claim against the retailer.

Every e-mail went out only after approval; deadline, tone and timing were mine.

The promised refund failed to arrive for four weeks; only a follow-up with proof of delivery of the return brought the answer: a technical error on the retailer's side.

A defective smart lock (Nuki), a manufacturer's support with ten-day response times, and the temptation to just buy a new one.

Complaints are won by whoever has evidence, legal basis and deadline in one letter — the invoice from my own archive was half the case.