minimum wage?

i have just turned 22 at the beging of august and i work in a creach i was paid £4.25 a hour be for i turned 22 and now i should be on £5.05 a hour but my boss said she wont pay me that untill the next months which is end of september its true by law that my pay should have gon up to £5.05 a hour the day be for my birthday and should my boss pay me £5.05 a hour by law now that im 22