where can I report an app?

I ve been a subscriber of the app “scribd” for the past year.. as a subscriber, I pay 8.99 & have access to “unlimited” titles of books & audio books.. recently I’ve noticed that all of my saved titles are becoming unavailable to most of my billing cycle.. only to reappear the day after my next billing cycle.. it’s infuriating! I’ve contacted their helpdesk, & only received canned responses that their sorry I’m unsatisfied... I think apple should review this app!! They are for

sure promising something for a price & not coming through with the promised product.. my only comparison would be if I tunes were to put a temporary hold on my music playlists for 3 weeks out of the month every month.. that would be crazy!!? Right!?

If you look though their reviews i am not the only person feeling duped..

dies anyone have any insight??