No I still have my account, and will proceed with the second chargeback if they don't refund the difference as I have requested via support desk.
The chargeback reason was simple: Incorrect Currency Used. It's a pretty standard chargeback reason, and I didn't even need to submit any evidence to the bank (although I took screenshots so I would be able to if asked). It was very simple.
I will be interested to see if they ban my account; I presume that would be a bad look for them. Frankly I'd love to get noisy about this issue; perhaps we can get some tech press coverage if we start doing it regularly and getting banned.