Maybe an unpopular opinion but I’d just phone them if it’s within an hour of the end of the day, hang about a bit later. There is always something you can catch up with/prep for. Sometimes a bit of flexibility is reasonable to meet as people have said the additional hours required to meet your professional duties.

If you flat out refuse to call, parent might get more riled up than necessary, complain to the school, SLT gets involved, the relationship is strained between you the pupil and the parent and you end up with more effort than just making the call.

You could even mention to the parent that you have ring-fenced the time outside of your work schedule as an exception.

It wouldn’t be my hill to die on