Eunonymous needs a doctor quick!

Please help! My eunonymous, grown from a tiny plant and now 4ft plus, is covered with a black sooty like substance, now both leaves and stem. I thought it was sooty mould but was told that this does no harm. Now part of the shrub seems to be dying back - sections of the leaves are now without colour and look like die back at least.

This is one of my favourite plants in the garden, so I am desperate to nurse it back to health. Any help gratefully received.

The culprit could be scale insects on the stems. These drain the energy from the shrub. I had a small acer dying back last summer and found clusters of the scale insects all along the stem. They also lurk on the underside of the leaves, and sugary sap oozing from the infested leaves gets attacked with sooty mould. Check to see, and if that's it then treat with Provado Ultimate Bug Killer. Organic insecticides won't shift it. 

Thank you. I'll go and see!