App - Device already linked

My daughter recently moved over to her fiance's Discovery medical aid. She's trying to access her app, but it keeps telling her the device is already linked. She went into the discovery website, logged in and delinked all devices. She uninstalled and reinstalled the app, but no luck. Each time she logs in, it just tell her the device is already linked. I can't find a link to this problem anywhere on the web.