Paying for an already paid up device

Vodacom is charging me for a device I have already paid for. My contract ended the beginning of April and late March I was offered a data and airtime contract to keep going, I took it since it was reasonable. now I am still being charged for a device. which device when my first contract was done? I didn't do an upgrade still using my old device. sooo Vodacom which device? yo'll are irritating