Sorry to hear you are having a problem. Not sure if this is your problem or not, but the Riders of Doom DLC will not show up in your Single Player as Riders of Doom. When you go to
Single Player, click Go Race and the last option to the right will be the
Big Sands (aka Riders of Doom) DLC. If this is not the case, please let us know and we will go from there. Thank you,
Did this solve your problem?
Sorry this didn't help.
Great! Thanks for marking this as the answer.
How satisfied are you with this reply?
Thanks for your feedback, it helps us improve the site.