My Victorian garden wall is 7 feet high and 20 inches deep. Five years ago I put some trellis up which protrudes 2 feet above the wall and 4 feet down the wall. The wall is predominantly random slate with a few stones here and their. The trellis was fixed onto heavy duty battens which were screwed to the wall with 2 inch plastic plugs. The recent storms was not kind to the trellis! Whilst nothing is broken the whole lot came away from the wall and was suspended in mid air by a network of plant climbers. I have managed to push everything back into the 20 holes or so and it is all held in place with a series of wooden props. Can anyone give me any guidance onto some more robust fixings that I can use. I cannot take the trellis down and need to work around it. Originally I had a terrible job drilling into the slate wall which would either take ages or splinter. I recently read that it is best to drill into a slate wall with a hand drill. I have tried this and it works really well. Are there any such fixings that will fit into a drilled hole and then "grip" into the slate when its screwed into? I see plenty of fixings that will do this for concrete but what about slate? Many thanks.