I have a Garmin Edge 530 ( £240 ) it has been defective from new, the elevation readings were 100 feet out, how did I find out? My Garmin Fenix ( £600 ) gave the correct reading. After numerous emails and a couple of months delay Garmin accepted it was defective and offered a refurbished replacement...for a NEW device, that was broken when I purchased it, to add insult to my expensive injury the customer has to pay for the return postage...quite disappointed in Garmin...no change that to extremely disappointed...get your act together Garmin treat your customers with respect...