Reversing a Receipt, correcting an error

I would like to get some ideas on the best way to handle the following situation:

A receipt has been done for 22,600.  Invoice came in for 22,400 and was processed (payment to supplier was processed).  We now know that the vendor is not going to bill us for the other 200 as they say they did not ship it.  Receiving then needs to correct. I'm not sure if a reversal of the voucher can still be done so that a reversal of a receipt and the correct quantity processed, what recommendations would you have for correcting the A/P side of the transaction as I know that I could use an IA or II to correct the