Please follow the below steps for Logged in with Wrong Mail ID:

Step 1: Check with the customer's registered mail id on the desktop application > profile..

Step 2:  Check whether the same mail ID is logged in the mobile application. If both the mail ids are different then the user will not be able to view the company data added from the desktop app. 

Step 3: Confirm with the customer which mail would be correct ( Desktop or Mobile app) and accordingly change the mail ID on Desktop or mobile and match it by guiding the customer on how to change on mobile or desktop app.

Step 6: If the desktop email ID is correct login to a mobile app with the same vice versa If the mobile app email ID is correct guide the customer with the email ID change process in the desktop.