since you can move up/down, that means there's power going to both mirrors, so can rule out both bad fuse or electrical issue.
seems like a left/right control bad switch issue, you may need to replace the door/mirror switch module ......
OR just forget it and set the mirror manually (have someone stand by the passenger side and instruct them which way to push the mirror) I really don't adjust the mirrors that often, only when I accodently move them when drying off the car after a wash.
I just checked, looks like tons on eBay, you'll need to replace the whole switch module, not that bad, like $40 used
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2141725.m570.l1313.TR0.TRC0.H0.Xcx-9+mirror+switch.TRS0&_nkw=cx-9+mirror+switch&_sacat=0
you'll need remove door panel to get the switch out... see video