I need help with a payment which has alrrady been deposited in my escrow account. However the payment is wrong?

I have charged $223.69 for 4 videos to be edited. And the buyer has accepted and deposited £111.85 in my escrow account.

Now...after a while of communication, they only want me to complete 2 videos now. Not 4.

So. They have already agreed that I wont charge $223.69 as that was for 4 videos. I will only charge $111.85 for the remaining 2 videos.

How do I put my invoice in now. As I cannot cancel my original proposal of $223.69 As the buyer has already deposited $111.85 in my escrow account.

So when I raise an Invoice. Do I just raise it for the amount we aggreed for 2 videos. Which is $111.85.

Please help.

regards