Hi @azthreads,
Apologies for any inconvenience you had to face using the plugin.
The plugin just inserts data from each user row from the CSV file one by one during the import. The billing details in the CSV file will be imported only to the corresponding users as in the CSV file. The only chance of the issue occurring is if the columns/rows are shifted when you opened/edited the exported CSV in your spreadsheet application. Please try opening the CSV file and check if the billing details are present in the correct rows themselves. If the data is shifted in the CSV file then please try exporting the users again and import it to the other site without opening the file in your spreadsheet application.