I understand 0345 172 0046 is currently working. Ask for Loyalty or say leaving TalkTalk when prompted and you should get through to someone to talk to.
You may though have to listen to a few lengthy recorded messages, but if you persevere you should get through to someone.
They are currently working Monday - Friday 10am-6pm
To place a cancellation you can call our Customer Loyalty Team during Business hours on 03451720046.
The line will be open from 10am - 6pm. You would need to state the reason for your call when prompted - cancel my service.