Ignoring my cancellation requests

I initiated the cancellation process with them over a month ago due to us immigrating to the UK. They claimed numerous times that they tried to contact me but I was unavailable, which is not possible as I am around my phone all day due to work. They then requested an address via email from where they could pick up the router. This was given to them via email. Nothing was ever picked up. I have now been billed for another month even though I'm not in the country. I opened another cancellation request but have received no response. They are quick to sign you up because this means they get to take your money. They ignore any cancellation requests.