Lost cashback from clicks

I lost clicks cashback because a cashier made a mistake with the sale, at protea glen clicks on the 14th of June after collecting my medication I had to pay a difference of R10 but the cashier rang something for R70 which I didn't know about and use my cashback for R45 which was on my card. After the reversal the manager promised me that I will get my cashback back on the card after 24hrs. But up until today I am still waiting, I went to clicks malamulele and they told me that once processed the cashback is lost forever even if you can do the reversal. I want my cashback back clicks.