Chargeback help

Hello
This is my first post so sorry if this isn't right.

I recent purchased tickets from stubhub and they debited my account for the money and then a few days later said the order had been cancelled. But I received no refund. When I queried this they said that I had ordered a chargeback on a previous order and therefore they had kept the money for the latest order.

I have no idea what they are talking about and if I'm being completely honest I don't know if I did order a chargeback for a previous order. But I cannot find this order they are referring to, even to find out. I have checked emails going back to 2014 and none of my ticket orders match the order they are claiming I made a chargeback for.

I called stubhub and they weren't helpful and couldn't even tell me the order I supposedly made a charge back for.

So my question is can they just keep my money? Even if I authorised a chargeback for a previous order, surely this is a separate transaction and if a bank authorised a chargeback surely this decision has been made by a bank and is closed. Can stubhub just keep this money for a chargeback that may or may not have been settled by the banks years ago?

Any advice appreciated. Thank you.