Service tax payment in old assessee code

Hi,

I am working for my ex-colleagues  partnership firm on part-time basis (Sundays only).

First, the auditor got service tax registration as proprietorship as getting PAN for firm takes time.

Later we got new registration with firm Pan No.

Two months back I applied for surrender of old registration but the request is still pending.

By oversight, I made payment of service tax for the month of may and jul on the old assessee code.  Both the registration is showing same details except the assesseecode

This mistake I noticed after filing apr-sept return and it was showing the error that, the challan does not exist in the account. Can I revise the return and show the two months amount in the old assesse code ?

Kindly advise what to do, as I am unable to visit their office becuase of my current job.

Thanking you all in advance.

Sivaprakash