Today I have removed a dead vine root that has caused some damage to the brick work on one corner of my house. As you can see from the picture below, along with the root a fair depth of stone has come away from the block, and I'm thinking that this needs replacing sooner rather than later, as it's the bottom brick supporting a 2 storey wall.
The blocks are quite big, so sourcing a replacement could be difficult, and removing the block all together seems like it could cause more harm than good. I have had a go at making a mix of broken parts of block and mortar to patch in the missing stone, but having that depth of mortar stick without sliding down wasn't working.I decided that this method of repair might not be strong enough long term, and have removed the new mortar.
What is the best way to fix this wall so that it looks as attractive as possible, and provides the maximum amount of support to the wall above?