Big businesses tend to suffer from frauds and scams and angry customers periodically so they expect a certain amount chargebacks and even out right thief.
Yeah, they have special accounts for that. It's generally called "Customer Retention" or something similar, and, going by SE's business structure (assuming, since I don't work there and I can only guess at this), it would be going against customer receivables. More likely around .5% of monthly income from subscriptions.
It's also just as likely that the chargebacks are being treated as rounding errors to the conversion of currency, as I highly doubt SE has a super-large accounting department (they don't seem to be the type of company that would have multiple location accounting departments going by their annual reports). It might be a question by their auditors, but this isn't something to even mention on the audit report.
It's only when the number of chargebacks or complaints reach a certain level that credit companies and banks safeties will kick in and suspend the monetary transactions of the company. In smaller businesses they will even close the bank account. That's when SE have to act.
It's more difficult for multinationals like SE. I don't know, and I don't think anyone here knows what Paypal's procedure is for chargebacks for large multinationals like SE.