hi there
how old is the property?? looks quite new from the pics, say built after 1995, facing brick work now can be very soft.
it maybe worth taking a look at a soda blasting solution on this, as you need to release the contaminents from the substrate, as opposed to pushing them into the brick.
alternatively, a spray solution of ultarpac renovate applied, then allowed to dwell, and absorbed back off the surface with pads, would provide a level of result, but at time cost.
better stile would be a pultice mix applied allowed to cure, then peeled off.
it is difficult, we recently looked at a fire damaged carpark, to clean the whole place, with correct procedures, and disposal methods, and another company literally turned sprayed it down and walked away, without taking any precautions as to where the contaminted water went.
so unfortunately you are not bidding on a level playing field.
regards
martin