Cancelled account

I have canceled my account and have been told I do not need to return the equipment as it’s over 10 years old. However I was also told I will receive a letter telling me to return the equipment, I am confused. I asked for a letter or email stating the equipment does not need to be returned and was told they can’t do that. 
How can I be sure I won’t be charged?

Talking to a call center halfway round the world just enforced my decision to cancel