Gst on non recovered invoice amount

Dear Members

I have raised a tax invoice on my debtor of Rs 10,000/- and paid 1,800/- gst to government. The debtor has paid me Rs 7,000/- and is not willing to pay balance Rs 3,000/-  on the reason of  defective goods / poor quality of service rendered.

What will happen to gst Rs 540/- on this Rs 3,000/- ? Can the supplier issue a credit note to debtor and report in gstr1 and thereby adjust this gst ? Would the answer be different had the ground of non recoverability of Rs 3,000/- been for other reasons.?

Please advise.

Regards

CA Dipjyoti Majumdar