Buyer disputing google play card bought already and says more infornation needed

My buyer is asking for gift refund after he bought a good card but the card only says more information needed which is unusual. I provided him all the information he was asked for and he still wants me to cancel please help me. He already escalated dispute

If you haven’t, for your side, you have to provide evidence (What evidence is needed is stated inside the article) in the chat side with Gameflip in the Dispute.
There are Details about how Disputes work and what Evidence is required in the article below.