Ooma Continued to charge after cancellation Other

I purchased a Ooma telephone for my home.  It worked fairly well the first month so I prepaid for a year.  AFter a month or so, I was no longer getting clear calls.  The phones themselves are pieces of crap.  So I cancelled the service, recieved a cancellation number.  They continued to bill me.  

I disputed the charges with my bank and called Ooma back and was told, we deactivated for 2 months so you could see the equipment.  I told them I was not selling the equipment and just cancel my account.  They are still charging me. 

This company should be brought up on charges.  If I cancel your service, I should not have to pay for a service I am not using.  Especially when it didn't work as advertised.