Reversal of Advance Payment after Bank Reconciliation done

Hi,

There is a mistake in the PO created. Advance was paid against the PO and GRN was also done. Now because of the error in the PO we need to rectify. For that we cancelled the GRN, but because there is an advance made, we are unable to rectify.

Now the advance payment is cleared and paid from Bank. Also, the Bank Reconciliation is done.

Kindly suggest what needs to be done to cancel the advance payment and then rectify the PO.