Stubhub Charged me $5,000 despite the fact I sold valid tickets, and will not respond to me San Francisco California

I sold tickets through StubHub to a broadway show that I could not attend.

I purchased these tickets from TicketMaster, they were 100% valid. I uploaded valid tickets to their system after sale. After show, buyer opened up dispute saying tickets were invalid. StubHub asked me to provide receipt of purchase from TicketMaster (which I supplied in less than an hour) and scan report from venue.

While I was still trying to obtain scan report from venue, two business days after dispute was opened my credit card was charged $5,200 for cost of tickets and all sorts of penalties/fees and email stated that when scan report was sent that they would "reopen" dispute.

I later sent scan report I got from venue to StubHub which stated tickets were successfully scanned once and then tried a second time and came back as already scanned. Either buyer allowed tickets to be duplicated or what is more likely they are trying to scam the system by using the tickets to get into the theatre and then they or had someone else scan them a second time so they could "cry foul" and get their money back.

When I sent scan report that my tickets were validly scanned originally I thought I would be "exonerated" and get my money back. Not only am I still charged, I can't even a response from StubHub as I have contacted four times over the last 12 days including with the scan report and have rec'd no response whatsoever.

Basic evidence in this case:

1. I have sold hundreds of tickets through StubHub over the years (I have season tickets to several sports teams and have games I often don't use) and NEVER ONCE provided tickets that were invalid
2. These tickets were 100% valid and I provided StubHub with receipt that shows I purchased them from TicketMaster
3. I provided all evidence that was asked of me once dispute was opened
4. I DID NOTHING WRONG in this tranaction, I sold and provided valid tickets, and did everything that was asked of me before, during, and after transaction
5. After providing all evidence, StubHub will not return any of my communication attempts.

As I stated I DID NOTHING WRONG, I provided 100% legitimate valid tickets for this event, they have no evidence to prove otherwise (there isn't any) yet I have been charged $5,200 and can't even get anyone at StubHub to respond to me despite providing evidence that proves my case.

These are extremely improper business practices. I did nothing wrong, did everything that was asked of me, and I am out over $5,000 and can't even get StubHub to return an email. How are businesses allowed to do this??