Some people play it more for MP, what a shocker. Cant u understand that? The mutliplayer can be so much more its insanely fun.
So then just wait it out. Obviously MP is not a priority. It is, first and foremost, whether you like it or not. A Single-player RPG. The MP, has always been just a tacked on item. It was never the full intention of the game.
Stomping your feet and having a tantrum going "I'm going to refund if you don't listen to my (single) demand!" Is childish, especially when there are something like 200,000 players a day who play Single player, and maybe 5,000 who play multiplayer.
Don't get me wrong, I've also told the kids crying "Fix this bug in Singleplayer or I'm Refunding!" It's early access and they need to deal with it, too.
I love multiplayer, but it's not priority. Getting the game working, and the features out is more important at this time, to the Taleworlds developers. Eventually, we will also have proper multiplayer updates, and not just crash fixes, and minor balance tweaks.
Making posts stomping about threatening to refund isn't going to get you heard in a good light, whether it be about single player, or multiplayer.
It will just get you laughed at.