Clarification about vat revised return

Dear Goodselves,
I am a Sales tax service provider. I have completed e-filing as well as manual return submitting procees for one my client (dealer) on 20/06/2012, as per the bills provided to me by him for the month of May 2012.

After that, he called up me again and gave some more purchase bills of the same month and asked me to help him by filing a revised return for avaing the ITC benefit.

My query is, What I am to do now?? Is there any option for filing a revised return??

Note:-

1) The dealer belongs to TAMILNADU

2) The form being filed for him is 'FORM I'