Doing an A level privately while being in 6th form + applying to study abroad

Hi so this is probably a really niche situation to be in but I am currently a year 13 student doing A level French, A level Spanish, and BTEC nationals level 3 extended diploma in film and tv production and want to study abroad (Italy specifically). The issue is that my top uni only accepts 3 A levels for consideration so I need to do another (I'm currently self-studying A level Philosophy). Is there a way for me to force my centre to enter me for it? (my head of sixth form has rejected all my past requests to study the course)