I filed a grievance, the day after they offered me a permanent position

I was coming to the end of my contract in work. I found out I was in the very early stages of pregnancy and was umming and ahhing on whether to inform them, however due to complications in my Pregnancy they had to be informed so I could have days off without it being classed as a sick day. When I came back into work I was told they weren’t continuing my contract as previously promised as I ‘couldn’t drive’ but they would keep me on a 0 hour contract, which was no help to me as it was no guarantee, unfortunately I had to accept this, however they messed up big time when they continued a different girls contract who also couldn’t drive, I filed a grievance which didn’t go all the way through because the day after I filed the complaint I had a phone call offering me a permanent full time position.