My Groupon account was hacked a couple of weeks ago and purchases were made by the hacker to the value of £800. While the money wasn't debited from my bank account, they were marked as Pending Transactions which meant I couldn't use my debit card / withdraw any money for 12 days.
Groupon were absolutely bloody useless. Every phone call resulted in 'we understand the problem, it will all be fixed in 24 hours, we'll confirm by email'. It was never fixed. I never got the confirmation email. I asked to speak to managers, was told this wasn't possible.
Tweeted them, tweets were ignored. Sent emails / used LiveChat, was just given the standard cut-and-paste response: 'We're sorry this has happened to you. We take your security extremely seriously' etc. I was beyond frustrated.
Eventually spoke to my bank, who were amazing and so reassuring - money wouldn't leave my account, I wouldn't be charged overdraft fees etc.
The woman I spoke to in my bank's Fraud Dept told me I was the 12th person she'd spoken to that week who'd reported security issues with Groupon - yet there's been no publicity about this (that I've seen).
I'm now going through the same rigmarole trying to get my account closed (emails going unanswered, phone calls resulting in 'I can't help you right now but I'll get back to you in 24 hours') I've even written to the Managing Director, who has also ignored my email.
If you have a Groupon account - even if you haven't used it for a while, like I hadn't - keep an eye on it and on your bank account. Or better yet, close it. Maybe if they lose enough customers, they'll actually up their security measures.