I just tried it there now as we speak on my laptop and its working fine for me. https://my.electroneum.com/ with Firefox browser, no problems whatsoever. That message was up last week when they were testing the payment system but its not there now on my phone app or laptop. Try clearing the cache and cookies or a different browser? I don't know mate I'm just making suggestions and trying to help. Or try it on the app on your phone see if it still the same on there?

UPDATE: Glad you got it sorted!