HELP! Wisteria problems

Emma Madden 891

We moved into a house a couple of years ago with a wisteria. I like my garden but am nowhere near an expert!!
It has only ever had 1 flower on it so I gave a feed last year and pruned it hard as usual (I have to cut it a lot as it finds it's way under the guttering and roof if I'm not careful!!)
Anyway, today I have gone to give it it's annual hard prune and things have gone very badly.
The crown at the bottom looks rotten in places then I started to notice some of the established trunks were rotten too.....then I noticed some wood worm looking holes.....PANIC!!!! I snapped some of the wood and can see some white larvae inside. 
I've also noticed what I can only describe as a red/brown coloured tiny mollusc looking things on some of the stems.
The crown almost splits into 2 and it only appears that one side was badly affected (some of the branches were just rotten) so I've ripped that all conoletely down to the roots but the other side I haven't. I have cut one of the branches the other side and it seems to have black bits in it....does this mean it infected too?! 
I'e
 Attached some pics because I really don't know what to do!

BobTheGardener

The red/brown things are a type of scale insect, almost certainly Wisteria scale, which are sucking the life out of it.  They can be rubbed off (wear gloves, it's messy!)  I would then leave until the buds start breaking, at which point you will be able to see which parts are alive.  Then continue by cutting back any dead bits to just above a live bud.

Busy-Lizzie

That happened to my lovely double flowered scented wisteria. The white grubs were pretty big, don't know if they caused it or if they were something like stag beetle grubs because the wood was dying. Didn't notice scale insects. The whole trunk died and rotted. But then shoots grew up from below, must have been the parent root below the graft. Grew up to be a new wisteria with long single flowers. I looked up about it and the general advice was to get rid of it as it wouldn't be much good, but it's been lovely and has lots of flowers so I've left it.