I have a 9" brick retaining wall 3' high behind which the garden has a slight incline. The wall has a crack which follows the brickwork joints from top to bottom.
Is there anything I can do to repair the wall without taking it down completely ?
The wall does have several drainage holes near the base.
Same as the others have said, Derek. Twisted stainless steel bar for crack stitching.
The main cost is the helical bar itself. You don't necessarily need the mortar compound.
Rake out the mortar on a few horizontal beds approx 300mm apart (vertically.) Give them around 50mm depth if you can. Put the bars in place and re-point with conventional mortar to match the rest.
It's the bar that does the work... not the mortar.