Storage

My iPhone 7 keeps saying storage is full, it is the ‘other’ section that is the highest at 20gb, I have googled it done everything that it says to do including removing apps, deleting photos and videos, clearing history and data in safari, nothing is making a difference, I have had apple support who talked me through a complete reset, that did resolve the issue for a few weeks but now it’s back to full. Can’t use WhatsApp or download latest software update. Any help would be appreciated