Problem logging into Starbucks app

I changed phones and all my data was switched from iphone 6plus to 7 plus all my downloaded apps were transferred....however my Starbucks app is empty....I called Starbucks and after 1 hour on the phone they could not reset my information so they suggested I contact you for help...They had me remove my app and reinstall the app...however when I put in my information like my email and pass word it tells me that someone already has this email, but it is my email..so it won't let me reenter my information because it says it is already in use...please help...my phone # is ***-***-**** in case you need it

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