Google play gift card issue

@DarkKnight @Sparkling_Juice I need help On trade# cd4391ce-c35b-452a-966a-0c5bf9a1c547, this buyer bought a google play gift card from me, redeemed it and completed trade after almost 24 hours he came back giving a negative review as bad card without contacting me and lying that I was not reachable of which my message box was open he gave me a bad review I checked card balance and it’s still there this means his account has problem and not from me he shouldn’t give a negative feedback just like that. I am actually new here and would not like to have a negative review on my profile can anyone please help me on what to do? My profile code is 44P837. Secondly , I’m trying to create a gameflip zendesk account but I am not getting the email.