Contacting Garmin to discuss altimeter/barometer repair?

The elevation recorded on my outdoor runs went nuts a few months ago. My watch is completely blotto - registering an 11,000m climb during my 5km circuit! I have done the usual calibration resets and careful washing of the device, and kept hoping a software update might patch this. Everything else seems fine. I have tried contacting Garmin support over 'chat', but security on my phone won't allow sharing of an activity (apparently). I have also tried the Contact Us email page in different browsers but there is no indication a message has actually been sent. This is crap! Anyone having more success and can suggest a tip?

Cheers,

               James