Given notice due me being part time

[Torialulu]

Hi, I was recruited to my role as an administrator on a 20 hour contract alongside a job share who was also on 20 hours. Since then my job share has left and they haven’t replaced her. I was told today that they are giving me notice because the admin position is a full time role.
i have been there 18 months so I know it’s tricky under 2 years service but do I have a case on discrimination for part time work?
I have a permanent contract and passed my probation with paperwork to confirm this.
There is no evidence that a job share didn’t work, we didn’t miss a deadline, we completed all tasks. No issue was raised during the job share. If anything we covered each other’s work when annual leave or sickness happened.
Is there anything I can do to take this on and it just doesn’t seem right or fair.

Thank you

[ULA]

Was there anything put in place in the event that one of you left?
Although it may not be possible for you, have you been offered the opportunity to work further hours?
Any chance the role could be done part time?
Do you know if they have been actively trying to recruit another job share person?