If you are out of contract then a SIM only upgrade through USwitch is usually the cheapest
https://www.uswitch.com/mobiles/compare/sim_only_deals/o2/
Choose the deal you want
This will automatically redirect you to the O2 website
Just follow the prompts and choose Existing Customer the the UPGRADE option
Complete the deal and nothing on your account changes except the tariff at the new cheaper cost
Payment date is the same and your next bill will be at a cheaper rate and will be made up of the pro rata cost of your old tariff and your new tariff
The change should show in My O2 within 24 hours
Volt benefits will still apply as will possibly a 3 month extra such as Disney+
This is not O2 and we are all customers here similar to yourself and cannot answer account type queries.
