Update employee letter for ACS review

Since I got a negative result, possibly due to less details in the letter, can I update the Employee Reference letter for the “review process”? Will ACS accept the updated letter signed by the same head who signed it before? Or the CO will only review the additional documents such as payment evidences etc.Please advice

“Review” simply means that relook at SAME documents.
If you change the letter, they will ask you to file a new application and pay the full fee again.

Thank you Anil for the response

So, theoretically we can apply a new assessment with new RnR (updated) letter?