use text service - 07533 051 809
they will respond, if not straight away, bit later, but they will:
- if you want upgrade, they will action it as normal
- if you want downgrade or cancel, they will try to give you better deal on current package, then to say they can't downgrade if you still insist on it - they will transfer you to 'customer relations and retentions' team. another wait, but they will come back to you 100%, just like they did to me.
if you are sure to downgrade or cancel - ask straight away to be transferred to customer relations and retentions team, as said you will wait a bit, but they will answer eventually.