How embarrassing and how spiteful of MFI not to help but my own experience of that company has taught me that they have no concept of Customer support.
When we moved house some years ago our removal company lost all the wire support hoop frames into which my corrugated garden cloche sheets fitted. I wrote to the manufacturers explaining my problems, and although it was their policy not to supply the wire frames separately, they did make an exception for me and allowed me to buy replacement ones. Have you just dealt with the local MFI branch? Could you try tracking down the directors (or the National Sales Director ) of MFI via some kind of Internet search and writing to them explaining your dilemma. You might get a more helpful response. In the meantime, I would press your removals company for some kind of compensation. (I don't suppose it's possible they could have been accidentally left behind at your last house by any chance?).