@Chester If your phone supports it then buy a MicroSD card and then select the option to move apps to the MicrosSD card.
Current Phone: Sony XPeria Pro-I and Motorola Razr 5G I also have a Planet Computers Gemini
I work in IT as an Enterprise Messaging and Collaboration Tools Administrator (Office 365, Slack and much much more) and manage hardware both Mobile and Desktop / laptop, my desk is a bit like PC World
-- We are all customers and dont have access to any o2 accounts
Buy a new phone with at least 64gb of internal storage.
I have no affiliation whatsoever with O2 or any subsidiary companies. Comments posted are entirely of my own opinion. This is not Customer Service so we are unable to help with account specific issues.