Standard bank 55-day "Interest Free" Gold credit card

I will try to keep this as short as possible regarding Standard bank's 55-day "Interest Free" Gold credit card:

Standard bank makes the above-mentioned product available to people under the pretense that for 55-days, you will not be liable for any interest for 55 days as the name of the product implies.

I had the features of the card explained to me when accepting this "amazing" offer as well as did my homework by going into the bank and making calls (spent A LOT of time) before lending the full R50000 for 55 days (for a project to invest through them by the way).

After 55 days, the money was back into the account, only yo find that they charged me the FULL interest (so R1300+) under the guise of "Cash Finance charges" and after 25 days (and LITERALLY more the 8 hours in the bank and on the phone), I am given the answer "...is only applicable to purchases (this is transactional purchases made at e.g. Pick n Pay or any other merchant). I mean, not even the Credit card consultant, bank consultant or the bank manager could explain this to me and kept saying that they are not experts in the credit card department.

If this is not seen as HIDDEN cost or false pretense, then I do not know what is.

I am VERY disappointed as a loyal client of 32 years and still want my money back.