Extremely poor service

My elderly mother lost her phone in July 2014. She was due for an upgrade and requested a new phone. She was informed that a new phone would be delivered to her home in early August 2014. When the phone was not delivered by the end of August 2014, and she could not get hold of the company telephonically nor by email. She cancelled the contract by email . To date the company continues to bill her monthly, does not respond to numerous emails. It is imposbible to get hold of them on the phone. How do we get this problem sorted out??