I work part time in retail. I am contracted to work three days per week: Monday, Tuesday and Thursday. There is a clause in my contract which means on occasion I may be required to work additional hours according to business need. I have provided my employer with my availability on Wednesdays and Fridays (which is 8am-5pm on both days) in case they ever require extra support during these times.
I have been put on a rota for a shift on a Friday, one of my non-contracted days, from 4.30pm-9pm. I have told my manager that as I am not contracted to work on a Friday, and because this shift is outside of my availability which I provided them with, I will not be able to do this shift. However my manager has told me I need to either find someone who can cover this shift, or I will have to work it.
AIBU to say that I don't think it is my responsibility to find cover for the shift?