Posted: 05/04/2014 at 21:38
Hi Rio, welcome on board
I don't cut stems back by a third. I cut about a third of the stems back to base and leave the rest.
I have completely demolished one in the past. It had lost all shape and was a right mess, so, kill or cure, right back to about 6 inches for all stems. After that it flowered better than it had ever done before.
In your position I'd probably take cuttings then get the saw out