Actually it hasn't been stated many, many times. People on the epic forums had to pull teeth and read between the lines of twitter posts for months to try to piece together a theoretical confirmation of its removal. Survival mode...isn't really comparable to horde. Its 10 rounds, classed based and basically just fast-paced skirmishing, like the campaign itself.

Horde mode coming by way of DLC won't really help any because most people don't buy DLC. You'd have the mode back, but with a community of around a third of all GowJ players at the height of its online activity. Just based on the general opinion I've seen from people so far, I doubt the game will even have the longevity that the previous ones did anyway, which makes buying the MP-based DLC less justifiable for most people.

You might be stuck with a gift card/store credit refund. Cash payment, you can get a cash refund. I'm not too sure about a cash refund for a credit payment.