informed that order has been cancelled, no refund

I bought canvas 2 for 1 print deals through Groupon from Printexpress online. I had a problem with one of my vouchers being blocked. Eugene from printexpress opened the voucher for me and assured me that the validity date will be until the end of September 2015. I processed my order and submitted it to printexpress in due time before end September and received an order confirmation from them. This morning( 13 November ) more than a month later, I was informed that my order has been cancelled because it was submitted after the expiry date. Upon confronting Eugene I was informed that Groupon won't honour the deal because it was late and he can do nothing about it, even thought he was the one who assured me of the timeline?! He refused to assist me anymore or to give me contact details for anybody else that might be able to help or his supervisor. This is unacceptable behaviour for someone that is suppose to be the customer liason person, to outright lie and cause a paying customer to loose their money.