Bad service

I have upgrade one of my sim card from data to airtime on sim card number *** a few weeks ago and I was promised that this upgrade comes with once off voucher worth R1000. The upgrade was done succesfully but there is no sign of the voucher that I was promised. Yesterday I have called Vodacom to find out where is my voucher, I was send from pillar to post. And I decided to send them an email and the lady by name Nonhlanhla Nakeng called me and wanted to transfer me to the department that will assist me. And refused as I was busy at that moment and asked her to just email or SMS the voucher detail to number *** or this email, till today nothing has been send to me. Why you promised the customer something and yo don't deliver, this bad service. I want my voucher now unless cancel both my contracts as you are *****.