I tunes voucher not received

On the 15th of Sept around 8 am, I made a purchase of itunes voucher via fnb cellphone app and I never received the voucher code via e-mail as supposed to. I made several phone calls from the day of purchase to the relevant call center, spoke to different people between being told they were off line, made to hold, sent from pillar to post. Finally on the 24th Sept '17 almost 2 weeks after the purchase, I received an e-mail from them with was what is supposed to be a voucher. When I tries to enter the number it gave me an error"You must enter a valid code", after several attempts with the same error I decided to call back the call centre. The same frustration again, I was made to hold, asked to click on the link that was taking me to an e-mail address which they said should take me to the relevant voucher just to mention a few. The last call I was told I should take it up with the network provider as there is nothing they can assist me with... almost a month of being sent from pillar to post I still didn't get assistance. I ended up telling one of the people I spoke to that I will never purchase a voucher from fnb so much for convenience as if I did over the counter @ a shop, it wouldn't have been this hassle.