Thanks for the replies, the drill has been fine with the other holes it's just a couple that can't drill deeper.
The window frame is relatively new but I can't see anything that would prevent the holes being drilled to the correct length.
The epoxy resin solution seems to be the best option...
Hi, I'm fitting a blind and I've managed to drill most of the 6x35mm holes for the supplied wall plugs and screws.
However, there are a couple of holes that just won't drill beyond 20mm. I think i have 2 options:
1. Use smaller wall plugs and screws (4x20mm) and pack the 6mm holes with...