POOR SERVICE, NO RESPONSE AND NOT OPTION TO SPEAK TO A SERVICE PROVIDER

I am trying to cancel a data contract without success. They promise to send a sms or e-mail, and if not received, the cancellation is not activated. After numerous calls and attempts, I am still not receiving any confirmation.' IT IS SAD THAT THEY CAN CALL YOU A 100 TIMES TO UPGRADE, ETC., BUT THEY PAY ABSOLUTELY NO ATTENTION TO CANCELLATIONS.