how do i repair the brick/mansory wall with plaster rendering?

[helloeatty]

 

 

  

first of all, is my wall a cement rendering wall or plastering rendering wall ? My house is double brick.

One of the wall in the walking wardrobe has been deteriorating due to the tenant having been laundry his cloths inside and also the bathroom sharing the same wall.

The corner of wall has already peeled and some mould? And yellowish thing can be seen. When I scraped the paints and the plaster rendering, the powder feel moist. And seems those rendering are not holding very well, and can be scrape down easily by some force.

so how do I approach these, to get the wall repaired