If you were affected, I think you can contact Groupon and request a refund. The Groupon offer was only valid for people from the US or Canada, so I wasn’t able to take advantage of it but based on what I’m hearing/reading, GoDaddy rejected additional Groupon credits today.
For example, if you bought three $70 credit codes via Groupon and applied them, you’ll only see $70 in your account now instead of $210. If you bought 4 $70 credit codes, you’ll only see $70 in your account instead of $280 and so on.
So only the credit for the first code you used is being accepted, the other ones have most likely been rejected.
Check your account to see if you were affected as well.
If that is the case, I think you can ask Groupon for a refund.
Never used Groupon myself but I’m pretty sure you’ll receive a refund if you contact them since the additional codes code you bought didn’t work.
If you already spent the $ on registrations/renewals/whatever, you will most likely not be affected.
Based on what I’m reading, it seems that only those who haven’t spent their credit yet are dealing with this problem.