Can't even get a basic answer on interest rates. Charlatans dealing in smoke and mirrors

The most untransparent bank you can find. Even their own consultants can't tell you what the interest rate is per package. I called to cancel the full "suite" option that costs aver R400pm and keep only my black credit card, which I use. I was told my interest rate would change from 16% to over 20% if I did so. Asked for documentation detailing this - still not received. Called in today to enquire what the "base" interest rate is per package - there's no info on this on the website, only promises of potential "better" rates based on your Vitality money status etc. I asked the consultant if rates were not based on an indivudual's credit profile. She couldn't answer me - could only spout that you get a few percentage points enhancement with Vitality Money. I reiterated that I wanted information about the actual rate, and did it differ per option black/gold etc. She said she needed to put me on hold for up to 4 minutes to try find out. After 23 minutes in total I was cut off. Is it too much to ask a bank for their interest rate info? Yes, apparently, if you are dealing with Discovery. They specialise in smoke and mirrors - don't like to give straightforward information