Just to keep you guys updated,
So far my PI has been quite honorable. They gave me a firm date for the part replacement ( 2 weeks) then the part arrived on time.
Also gave me a loaner car to drive while it was being replaced (BMW 5 series!)
Due to collect my car back tomorrow, hopefully everything goes well now!
Despite all that's happened, I think this is one PI I'm happy to work with. They've gone quite a bit to try to troubleshoot for me and then fixed it in a decent time. (After all, the original fault is probably not their doing)
As an aside, for the last few days I've been getting a lot more vehicles trying to cut my lane, preventing me from overtaking and generally being agressive when I'm driving he BMW as opposed to my Toyota. Even got the middle finger from a Mercs who did a left side overtaking when I was driving behind a slow vehicle in the middle lane and tried to cut me off from filtering left. Is there something about BMWs that infuriates people, or is it just my conservative driving (I drive the family around in an MPV usually. No room for "vroom-vroom")