Hey camshuvash,
Thanks for posting in the Apple Communities! So you've changed the payment option but your storage space was not upgraded? You are spot on about manually upgrading your storage space. Please have a look at the links below to learn how to manage your iCloud storage.
iCloud storage upgrades and downgrades
Manage your iCloud storage
These tips will help you to stay on top of your storage usage and space. Thanks for upgrading your iCloud storage.
Cheers