So you dropped the ball on this one, that much is evident. DowIII is a flop. Peak users are lower than games released roughly 18 months earlier that have no appreciable multiplayer which is shameful. No one can continue to defend this game and its reception. DowII is a failure and its important that everyone accept that.
Now, you need to ask yourself where you go next to try to make this right with a justifiably angry player base. If you are thinking about turning a profit on the expansion, you need to stop yourself right there. It will not make money because of the sheer disappointment over the original release of the game. As things stand right now, the expansion to the DoWIII game (when it eventually is released) will be the first DoW title I do not purchase. And I'm sure I'm not alone in this sentiment.
However, I'm not saying that you shouldn't release an expansion. The DoW brand has value and all of your efforts right now need to be aimed at saving the value of that brand at the expense of profits on the next expansion. What do I mean? I mean you need to practically give the expansion away to anyone who bought the original DoWII release (after you identify all the places you went wrong and completely revamp the game). You need to make the disappointed players feel like you're looking out for them. Right now, it feels like you just used the brand people have great faith in to turn a quick profit at the expense of customer satisfaction. I find it difficult to believe you couldn't see this coming.
The people on this forum who have taken the time to try to explore ways to improve the gameplay and make the game fun are the ones you should be listening to, not the random gaming critics who played for 3 hours and slapped a seal of approval on the game. Trying to fix the game under the current DoWIII release title will be futile. The game's reputation has seen to it that even if you fix the game in theory, you will not see a revival. That is why you need to get your team to work immediately on an expansion release to save the brand while there is still time. Admit to your disgruntled fans that you dropped the ball and tell them you will make things right with the expansion not only in content but in a steep discount.
That is your only hope in saving anything. Saving the game under its current release title is going to be impossible. Pivot and focus on saving the brand and preserve your ability to make money on the DoW name in the future by taking a hit on the expansion in the short term.