Currently on her enjoyment list - Food. Food. Food.
Any suggestions how I can use that to my advantage without bribing her?

I am picking up a friend for her in the weekend, another mini but one with much better handling, so this could be a help also. Currently she is totally alone without a horse in sight as my big horses want to murder her.

You are right in changing her expectations, currently she expects if she is caught then she is locked up in her yard until the morning. I have been brushing, plaiting, washing, taking her to the back lawn to investigate kids pool and toys and cat etc and generally mucking around with her as much as I can to keep her mentally stimulated, being alone right now is hard on her.