I figured I'd update the few people who pop in from time to time as to the final outcome of my dealings with Rosendales...
After going down the whole complaints route with the LAA and getting nowhere I went to the parliamentary and health service ombudsman, after a year of investigating my complaint they have ruled in my favour! Legally I'm restricted from revealing the full details but needless to say I was right and they were wrong, any debt has been cleared and I've got a juicy compensation cheque coming my way!
Just goes to show never give up hope.