First time poster here, but need some suggestions / help. Thanks in advance.

So I have blinds in my reception (heavy faux wood blinds), which were fixed by the previous owners. The blinds are fairly heavy and long (about 1.6m in width, along the window and around 2m in height), and they require a fair bit of force to pull up.

The problem is that one of the holes which is used to mount the blinds to the wall (concrete, I think) is not straight into the wall, but at an angle, which makes it difficult to put a screw in there. Every time I try to put a screw in there, it comes loose after a few days and it appears as if the blinds will fall from there. Is there a way to fix this, without moving the position of the blind mount?

Am in the United Kingdom, if that makes a difference.