Vodacom credit voucher for cellphone warranty

I took my phone in to Vodacom repairs. The phone was still under warranty. The phone could not be repaired and I was given a credit/voucher number to get a new phone.

The old phone was an online upgrade which meant that I must get a new phone at Vodacom (online). The store whe I tooky phone in cannot help me. I called the call centre and no on knows how I can get a new phone or redeem the voucher.

Vodacom please help