pls help. which 1 is correct?

a) With regards to your Autopay query, once the account migrated as a Single Billing the Autopay service will automatically being cancelled.

b) With regards to your Autopay query, once the account migrated as a Single Billing the Autopay service will be automatically cancelled.

c) With regards to your Autopay query, once the account migrated as a Single Billing the Autopay service will be cancelled automatically.

b