No there is no provision to lower tariffs.
If on refresh you can pay off the phone (so it's yours) and just walk away. You can then get a sim only deal from another network.
You may also need to unlock your O2 phone to do this
http://community.o2.co.uk/t5/Other-Products-Services/Unlocking-an-O2-phone-to-use-a-different-SIM-ca...
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.
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