As an ex open reach engineer I have never heard of this before . I can only presume your parents have there broadband connected in the exchange rather than the green box an openreach are turning off the exchange and sky have no ports (DSLAM) available to them in said green box ,if the broadband was connected in the green box then nothing would need to alter
I don't know. I've exhausted every option with Sky, I'm sick of phoning them. Openreach a company you cannot access via email or phone etc which is ridiculous. Every option ends with message "contact your provider".