Cancellation nightmare

No matter how hard I try or how many phone calls I make, I cannot cancel my LTE Sim card. I think they do this purposely. It is month to month and I have had it for over 3 years - you have made your monies worth out of me. I get shoved from pillar to post, then the call drops - Bravo as it is their own network - then yoj get put on hold then after all this I can't get a reference number. I know this game - it then becomes a game of my word against yours. I want my reference number.