My reply is not based on any expertise, just some experiences. Do you have any expansion joints on that particular wall?
On my development, one of the builders is Persimmon. An acquaintance has bought one of their houses. In passing one day some time back, he showed me something on a neighbours property, which had similar red bricks as yours. Persimmon had failed to provide an expansion joint, on one wall and so a worker cut one into the brickwork using a 9" disc cutter from top to bottom.
However, they didn't use any sort of guide nor dust extraction. So the end result looked like a crinkly chip, and neighbours with pink coloured cars.
Hope you get yours successfully rectified.