A few points for you too consider.
1. The only way you will get a refund is through the retailer you bought the game from, not from Bethesda itself
2. There is a line of code in the 1.8 Beta that specifically mentions PS3 DLC, moreso too add the in game DLC menu. Make of that what you will.
3. This thread will probably be locked and you will be redirected by a mod to the PS3 Dawnguard Thread, where we supposed to talk about the DLC or lack there of on the PS3
Hope this may be a little enlightening, or helpful. And I see I'm a few posts off, but welcome to the forums