Please reduce cash withdrawal limit on my credit card to R500

I have an FNB credit card and use online / app banking. On my cheque card, OB allows me to set cash withdrawal limits. Since I have a low requirement for cash this has a R500 max daily withdrawal. For the credit card, the limit setting disappeared from OB some time ago and I cannot see the current cash withdrawal limit or reduce it myself. When I phoned FNB credit card they told me they could not reduce the daily withdrawal limit to R500 as I wished and I must speak to authorisations. I did and they said they could not do this. I am therefore sitting with a potential much higher cash theft possibility that I do not want. This is ridiculous. Please have some one with the authority to change this call me.