Leaving Three Broadband
How to switch from Three Broadband
If you are switching between broadband providers that don't use the same Openreach phone network (i.e. a broadband provider that is mobile, cable or fibre only), you will need to manually cancel your broadband service with Three Broadband.
Three Broadband will confirm with you the exact date that your contract will end, and the amount of the final bill. Note that if you are leaving before your minimum contract term is up then there is usually an early termination fee for ending your contract early.
To avoid being without any broadband service during the switch over period, ensure your new broadband starts on or before the date that your old service ends.