Send them a note advising that you will initiate a chargeback for the port and venue fees if a refund is not issued within 7 business days. On the 8th day, initiate a chargeback for that amount. Make certain that the chargeback specifies the fees. Not worth your time chasing stuff. Make one ask and then follow-up.
Remember that while most card issuers now permit chargebacks well after 60 days, the law only allows you 60 days. So time is not on your side.