Required assistance to purchase the Cubase Crossgrade service

HI Cubase Support team,
I am interested to purchase the Cubase 12 pro through your Competitive Crossgrade option however i am getting the following message while processing the address details.
Your e-mail address is already used in the system. Please choose another e-mail address or use your old account.
I am the Cubase elements 12 user and would like to upgrade to Cubase pro 12.I had also received an email for the Eligibility verification but unable to process it.Any help would be highly appreciated.

crossgrade is if you come from another program to Cubase, say you own Logic then you must show documentation you did buy that program and you get a discount for the crossgrade. If you already are an Elements 12 user you should pick the “buy Cubase 12 pro upgrade” then find the option to “upgrade from Elements 12, Cubase LE 12, Cubase AI 12” which would be the correct update for you. Then you must log in with your old account and upgrade with that information.