Existing customer changing tarriff

[LM4]

I have a contract that is due to end on 16th July 24. I found an offer from Uswitch that, without logging onto that website, brought me to my O2 account page (that I previously had signed in). The contract is now in the 02 basket. However, if I purchase this 12 month contract will that start immediately after the conclusion of the existing contract? Do I have to terminate the existing one before purchasing the new one? It's very confusing and telephoning them appears to be no use.

[Bambino · Accepted solution]

@LM4 See below, which is from another thread:

Use USwitch to get a better deal.
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 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+.

[LM4]

Thank you for your reply. It was very much appreciated.