stained and cracked render

hello all

we have cracks to the bottom corners of windows going diagonally about 30% of the windows are affected

we also have water staining coming through on the below ground external walls these are walls holding the garden back from the basement garden

we also have water staining beneath and at each side of the coping stones to these walls

i know we can discuss these issues all week but i need a definitive answer so is there anyone who can survey it and tell me what is causing it...

stained and cracked render