Groupon is impossible to contact via e mail

I placed an on line order for 3 items with Groupon. Strangely my card wouldnt work (this never happens to me with other on line purchases) and so I was forced to make an EFT payment. I made this but when I tried to use the e mail address given for Groupon to send proof of purchase to it is a non existant address. I am out of the country and unable to make a phone call to them....will never ever use them again....makes me wonder why no e mail address is available for them.