Ok I am not sure if anyone else was having the same issue as me but I would break form and it would only cast on me it doesn't matter who I clicked on HB.
So the solution I posted ... seems to be working for me.
It's not my own just something I found through digging.
Ok I found a fix that works it will break me out of form cast Rejuv and then I am free to shift back in or carry on healing.
I tried many variations including @hbplayer and @player and this is the only one which worked properly.
The targetlasttarget I'm not sure why it's in there but it doesn't do any harm. I found this on the Warcraft Forums after spending some time Googling, I'm not sure if it will help anyone else but for me this is great.