I think the bottom line is - you're screwed. The "friend" and the flight school did you no favours (but they did make lot's of money out of it, eh?)
My last chat with the CAA about someone in a similar (but by no means identical) situation (i.e. 12 months about to expire) resulted in the Authority saying words to the effect of "the application has been made within the 12 months so should be honoured by us when the shortfall is corrected".
Whether they'll actually do that is a different matter. The CAA change their mind at the drop of a hat - or threat of legal action.
I suspect you did a single engine CPL test so the class rating part should not be a problem. Have the authorities issued (or even offered to) the multi engine piston rating and/or instrument rating to your PPL?