Fair point. In future try to use the 'Report Post' button to inform us, then I'll get an email telling me and I'll likely come and sort it quicker anyway
You can buy the Undead Nightmare disc and play it standalone, but if you download it you'll need the full game. You can probably get the full game for a similar price now anyway, so if you don't own it yet I'd just buy it and download the DLC. RDR is easily the most popular choice on other forums I visit for game of the year. It is certainly mine.