policy keeps on canceling

every 3 months or so they just don't deduct and cancel my vitality WHY ??? why not call me and advise the debit did not go through , in fact why did you not deduct as there is funds ? every time I need to call and hear a consultant say I don't know why it cancelled , I called in twice and the call was dropped on the first and 2nd call , why don't you even call back ??