Seems like a common rejection when an app is just a repackaged website. Not much to say but add functionality.
Try making a native iOS app that showcases the platform.
If you want specific suggestions otherwise, you'll need to talk about the app, beyond just why it was rejected.
I am also trying to submit an app which has almost all functionality of the website, thought it has some more features, like notifications, buttons in footer for account, cart and home page. A left menu etc. The app got rejected twice.
I am thinking to add a call button in app (which was supposed to be added in later updates). Will it be helpful.
Any other suggestions that can be added to get it accepted.