Crap seatposts - money saving bodge up advice please

So, I currently have a cheapo bog standard seatpost which doesn't have a 'ratcheted' saddle angle adjustment, i.e. you just loosen the bolt, adjust the saddle angle (I keep it flat), and tighten the bolt back up. Problem is, I find that no matter how tight I tighten it (and I fear the bolt breaking), the fucker moves after going over a good few bumps (I try and unweight in advance but not always in time).

Before I invest in a new seatpost, is there any way of bodging the cheapie ones, safely, so the saddle cannot move out of place? Its pretty unnerving when bombing along and you go over a bump and the saddle suddenly moves. I was thinking about trying to drive another bolt into the slot in the seatpost, on either or both sides of hte one that holds the saddle in place.... thoughts?? advice?

mmmarrrrrccccckkkkk

not sure about your seatpost but you need to get you kkkeeeyyyybbbboooaaarrrrdddd fixed

roughen up the surfaces or file some lines in. you could also put some superglue between.

i use a crappy kalloy micro adjust post and it's one of the best things i've bought
http://www.freemanscycles.co.uk/images/saddles_seatposts/seatposts/Kalloy_seatpost.jpg

could bodge a home-made shim on the saddle rails?