Not receiving the data as signed in the contract

I signed a Vodacom contract about a year ago with Nashua Mobile, as per the contract I was meant to receive 200mb data and a further 200mb promotional data per month for 24 months. Since they closed down and handed the contracts to Vodacom, I only receive 200mb and don't receive my promotional data as promised. I phoned Vodacom many times, but they cant seem to sort it out