Maybe this can help some people….
Advice for responding to employers asking for you to work outside of your availability:
JUST SAY NO.
If they press for an explanation then tell them your are unavailable. If they press more than say its a prior commitment. Alternative between those three things: no/unavailable/prior commitments.
No other details required.
It does not matter what that prior commitment is, do not tell them no matter what, they will only keep at you and make it personal.
Work is work. They dont need any details about your life. Say no, be firm in the no. Give no explanation or details. Dont respond with “I cant” . Just say No. No is a complete sentence. “I cant” gives them an opening you dont want them to have. Dont invent anything to tell them either, just tell them no.
Eventually they will move on to the next person on their list.
If you can and want to pick up the extra hours and shifts then just say: yes, I can do these hours (xx:00 to xx:00) does that work for you? Or just say yes.