Excise item sent against warranty claim what are the docs re

Hello,

We have sold a Excisable commodity to our customer X later due to quality issue certiain items we need to replace them under Warratny to our customer X Now I want to know

(1) How I have to send this Warranty material to my customer X ( It has to sent to customer on free of cost as it was under warranty)

(2) What is the documents (whether Excise invoice or Jobe work challan) are needed for this clearence

(3) As it is free of cost how i have to pay the Excise amount on this transaction?

Kindly suggest the necessary procedure in this regard

Thanking you in anticipation

Kishore