GIFT VOUCHERS ISSUE !!!

I received two gift vouchers for my birthday in October 2020. I wanted to use them this morning (06 April 2021) at your new store at Retail Crossing. I asked the lady to please check what the amounts were on both vouchers. She ran them on the computer and one was R300 and the other R400-00. On trying to make my purchase – I was then told – sorry, gift vouchers have expired?! She takes my vouchers and says, sorry, you can’t use them and puts them on the counter behind her. Luckily my sister was with me. So she ended up paying for everything on her account. Approximately R2474 worth of goods were bought. My question is – what happens to the R700-00 vouchers?? It doesn’t go back to the people who bought the vouchers? So Milady’s have just received a free R700-00?! I was told that the vouchers expire after 3 months?!?! I told them in-store that I wasn’t aware of this!!! The lady said, if that was her and this happened to her – she would be SO ANGRY because R700-00 is a lot of money!? I said, well I didn’t know! What must I do?? She said sorry, you can't do anything. They expired!?!? They kept the vouchers! 4 people witnessed this incident! Can’t those vouchers be renewed?? So Milady’s just scored R700-00!? Since then, I've had contact with the Store Manager (after sending emails to Customer Services), the Store Manager confirmed she had spoken to the Cashier and that the vouchers were thrown in the dustbin. They wanted to speak to the people who I received the vouchers from - as some sort of proof - i.e. exactly when it was purchased and how etc etc - she's been very helpful and has apparently handed this to her Area Manager to escalate and revert! Today is 21 April 2021 and I am still being told the same thing. Waiting for Area Manager to revert. If I don't keep asking about the R700-00 vouchers, it will most likely be forgotten about and just ignored and Miladys have received R700-00 for nothing! Surely this is not right? I need this escalated and sorted out!