Karina - I'm not a lawyer so don't take my word for it but I think there's two issues here. Legally, I think you are only entitled to your FT job back so they're within their rights to say come back full-time or if you don't want to, then please resign. HOWEVER, obviously morally they have done the wrong thing by reassuring you that you could come back part-time and then basically, changing their minds. But I would think if you don't have this in writing, then legally it will be your word against theirs. But if there is another part-time job in the company, I would speak to HR about that one (perhaps dropping very big hints that you're taking legal advice about the change of mind) and maybe they can just slot you into that one.

I would also say that if they're so far behind then why not get a FT contractor person for your original job with you coming back to work part-time in addition to that person. Then perhaps down the track you might want to go FT again and you could have your old job back.

I agree it completely sucks - this inflexbility is exactly why so many mums don't re-enter the workforce at a time when they are telling us there's a skills shortage.

Good luck with all of this and DEFINITELY find out your rights.