3x R150 Nandos Vouchers are not working!

I purchased 4x R150 Nandos vouchers on the Vodabucks store app. Only one of those vouchers worked, the rest kept throwing out an error code. I had to pay over R400 in cash to collect my Nandos order. This is unacceptable! I wouldn’t have placed such a large and expensive order if it wasn’t for the “great half price deal” on your app. I am now sitting with 3x R150 Nandos vouchers that DO NOT WORK!! I have tried numerous times to get hold of someone through your call centre but “due to the high call volume that you are permanently experiencing”- I am never able to get through. My vouchers will be expiring soon and I am not going to allow vodacom to scan me out of my hard earned money. I will be taking this further through various social media platforms aswell as legally if I do not receive assistance promptly.