Thanks ladies. I ended up just writing a fat arse letter to them on monday. I wrote about a page and a half just outlining the things I was told + when, and how I added an extra point on my contract & offer of employment that I would come back PT, and that I know they have PT positions available so they cant tell me they dont employ people PT. I also rambled on about how I had made attempts to negotiate something but all my offers were rejected by them, and they were the ones being inflexible...

Anyways, I got a call from my manager telling me that there is a part time position available in another office (the pt job i mentioned earlier) and he'll get the person advertising it to give me a call. He said I might be suitable for that job.

DH answered the phone when my boss called and he said that he sounded really quiet and apologetic/guilty. When my boss called last week, DH said he sounded differnt - like more confident and annoyed as if I was just taking up his precious time.
So I think I may have made him step back and consider the situation.

I am just waiting for a call from the person about the part time job. If it suits my (ie hours and location etc) then I'll consider taking it. If not, then at least they tried to help me, even if it wasnt until I had told them off.