Bad sevice

My husband and I each received our R400 checkers vouchers for completing our vitality health check and planned to use it for our food while on holiday. We got to the till and were told that it was invalid so we had to pay for the groceries and this has set us back so much as we had worked that money into our trip and now had to spend it on the food. I followed up via WhatsApp and spoke to onika, she first said there is 3-5days turnaround time and they cant give me a new voucher yet. I explained the situation and asked her to escalate it and she said she would and would mark it urgent and get back to me, that was 8 Jan and I still have not heard from her. I then followed up again, and still nothing was done, followed up again then was told this has been a problem with all LA health vouchers and i would get my new voucher by latest Friday 16 Jan...I still did not receive it, I followed up again today and they say its now 5-7days turnaround time, I sent a copy of the last message and was told the problem is still not resolved so now I just have to wait till whenever..this kind of service is not acceptable, no communication from discovery about the problem, empty promises and it has put me out of pocket.