Ok, so I downloaded GRA the first day and got the achievements. A day or two after the DLC release, I deleted it. I know they found a fix, so I did what was writen and I recovered my gamertag. It worked, and the achievements were reset so I can unlock them now. Today, I went to redownload GRA, and it says that I never bought it and I need to pay 320 MSP again. What can I do to get the DLC back? I don't want to pay another 3-4 dollars for the DLC if I already bought it.

Look in download history and try to get it from there. If that doesn't work, call Microsoft, they should be able to credit you or make it work. Did you charge the points to a credit card or use a MP card? Those each have their own solutions I can tell you about.