"Unable to link Polar account address is already in use" - FALSE

After numerous conversations with the consultants of the Discovery Device department, none of them can link my Polar M400. It always gives the following error: "Unable to link Polar account address is already in use" I never received an invitation email to link the accounts. Vitality is useless if I can't earn points on my device.

I canceled my Vitality during the year 2017 and reactivated it in January 2018 hoping the problem will not persist but yet again I am struggling with the same error. This is pathetic from their side because each time they just send it through to their technical division and they just give me a general fix it solution which does not work.