Had similar experience with them last September - turned our GPS on a day or so before we headed out for our hols in Wales and found its internal battery had gone, so it wasn't retaining any information about anything ("Satellites? What satellites?").

Rang Garmin, explained the situation, drove down to Romsey and they also gave me a replacement free of charge. Previously, they've sent us a replacement antenna in the post after ours got broken by accident. No fuss, no bother, they were happy to help.

Top customer service, and this thread deserves more visibility so I'm gonna slap it on the front page.
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simon