Having recently had my Sprint Mot'd, I thought I'd give her a run out this weekend... However I noticed that the rear near side door would not open from the outside and more alarmingly neither from the inside too...

Before this issue occurred, I was aware that the black locking button did not lock the rear door, it just gave the illusion the door was locked. The door could be opened from outside or inside with no problems...
Am I now faced with butchering my door panel to open the door or is there a more subtle way that I can get the door open and repair/replace the door linkage?
Is there a garage or professional person that can do this sort of thing?
Thanks Dave