Do you know how to give you're companion a power for promotion? Is it like, when you choose an epic talent, you can swap it for a power, or does it depend on if its the first or second promotion, or how does it work?
The only time a companion has gotten a power for promotion so far is that after i gave the epic talents I saw a new power in the corner but i did not get to choose it.
This should be covered in the Player's Guide but I'll give my basic idea.
When a Companion is ready for promotion, he/she says that they need to talk to you in a Tavern (doesn't matter which one). When you talk to them in the tavern, they will either tell you about a Quest they need to complete or how much Gold you need to pay them. If it's a quest, then you have to complete the quest. If it's Gold, pay them the amount of Gold. Then you go back to a tavern and talk to them again. Afterwards, you need to bring up the Companion Management Screen (press 'u') and select the Companion that has a Yellow Lightning Bolt in its portrait. Below their portrait, there will be a button saying Epic Talents that you click. You can then choose which of the Epic Talents that are listed that your Companion can learn. And that's it in a nutshell.
If after a time, you want to change the Epic Talents learned, go to the Companion Management Screen, select the Companion you want to change, and click the RESET button at the bottom of the picture. I think it is RESET and this is what I have done for a few of my Companions. I was able to pay about 1500 Gold to do this (don't know if being a member meant I didn't have to pay Crowns or not).