Unsuccessful online purchase

I was looking to buy a 9 kg front loader on the blue dot sale. I have credit card with standard bank and I saw that I can use the budget option and choose whichever months I prefer to pay but it doesn't want to process the transaction. The error message said contact customer support which I did and the consultant told me I must use mobi credit which I don't want to whereas I have an option to pay with my standard bank credit/debit card. I called samsung call centre on *** and I was told to call my bank. I also couldn't get assistance with the bank too. I have 3 options to choose to pay and I prefer the standard bank 0% credit card on budgeted months option.