Some time ago our side gate was replaced with a brick structure and around top gate (see photo) unfortunately the builder used the same standard facing bricks for the top layer laid on their side. Long term weathering and water ?frost etc have caused the top layer to start to break up. They need replacing with engineering bricks which I have sourced. My problem is to ensure that I have the right tools to remove this top layer without disturbing the underlying structure or the rendering which is on the outward facing part of the structure. Currently all I have is a brick bolster I have a strong feeling in the general waterworks that this is not wot I should use to accomplish this task without rending of garments and kicking next doors cat. advice please for which eternal thanks.