Do manufacturers 'guarantee' their watches accuracy?

Major brands put a lot of emphasis on their watches stated accuracy and in modern times the length of their guarantees. But does anyone know how long they guarantee their watches accuracy? When I bought mine it was within specification (just) but has since deteriorated so it is several seconds per day out of kilter. It is not awful (yet), but it has steadily got slower. Has anyone ever tried to get a (major brand) manufacturer to regulate a watch 2-3 years down the line?

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If it's out of spec and still under warranty, I'd expect the brand to regulate/service as needed for no cost.