Endless issues trying to cancel my contract and migrate to prepaid

Hi i have been calling countless times since march, my contracted reached its termination date on the 3rd of April, i requested that my contract be cancelled and migrated to a pre paid line, i was informed this would be done by the 1st of May last debit order to go off end of April, so the debit order went off and i waited for the migration to happen, i have been calling from Tuesday the 3rd of May saying this has not been done, i was told yesterday that the migration would take place at midnight and still nothing has happened i keep calling in and get told no i am still on contract i cannot keep calling and asking so what i did was blocked all debit orders from my account for vodacom, i am not sure if this is a way to make money by a month to month basis or not, i was told countless times i would receive a reference number for my call and i am still waiting for one.