Some years ago my builder fitted oak fence panels and concrete spurs in a section that was prone to waterlogging and wind damage. These have lasted well, not like some of the panels which are showing their age. I removed one and thought that it would take 10 minutes to fit a new one. The old panel was nailed in so I dutifully prised out the old nails and bought 4 panel clips from B&Q. I now need to screw these into the posts. I can't find a drill bit that will drill into the oak. I got a special wood-drill one and this won't really work. I've tried the hammer setting (not recommended!!) and all the speeds on my drill. Any specific suggestions? I suppose nails might work but I want to do a proper job.