Game pass ULTIMATE

Hi can any1 help me with this question please ive had ULTIMATE for 3 moths now and i cancelled my subscription TODAY as im im just happy with plain GOLD LIVE PASS now that i have cancelled the ULTIMATE i cant seem to buy a 1 minth GOLD subscription ,ive
ilso been to main settings in console and on web store to turn of auto pay and ive just put 15$ in myy xbox wallet but cant buy it even though ultimate will run out today and have also cancelled it do i need to wait until the exact time of day like 3:30 pm
if i subscribed 3 minths ago at same time of 3:30 pm

:)