Bad Service

My 2 Contracts expired on the 30th December 2017,i called numerous time asking for the feedback none of them gave me Sense regarding my cancellation and now i was billed for January and my contracts still not cancelled this is totally unacceptable because this is 24 months contract not 25 months , and what make me more sad is the fact that i sent them cancellation letter on the 04 December 2017.