Pebble dash advice and choosing a builder?

Hi, I have a 1930's semi-detached house with pebble dash render. I have some penetrating damp to the rear wall and outside there are some cracks to the pebble dash render that have been filled (not very well), before the wall was then painted white (not very well either) - thie cracks seem the likely cause. To rectify the cause one quote I have had is to re render the entire back wall of the house - there are some other cracks and a cemented-over flue and possible other areas of damp inside too, aesthetically, this would be nice to get it looking better anyway.

I would like some advice on the proper way to do this please. One builder recommended repairing where the cracks are and then re pebble-dashing the whole of the back of the house by putting more cement and pebble dash over the existing pebble dash. Does this sound a reasonable method, I'm not too sure! If not, how should it be done. Thanks for your help,