Good morning
I filled a Eurocard to the value of 300 euros paying about 12.57 South African rands per euro. The bank has a condition that if one reconverts what’s left on the card later, one gets rands back at the same old rate one paid originally (12.57. Meanwhile the rand has dropped so the rate is 13.8 rands per euro. Someone borrowed money using that card and now wants to pay back in rands.
If they pay back the euros (in rands) according to the new higher rate (13.8), would that be ribis? Also, is there anything ethically wrong with getting more money due to the friend borrowing money through the card.
Thanks a lot.

From the question I understand that the borrower received his loan in rands.

If this is true, the borrower must pay the loan back in Rands, and if he will pay more Rands that he borrowed, this will constitute a problem of ribbis.

The fact that you used a Eurocard to get the money does not change the nature of the loan, unless a special arrangement is made whereby the loan is defined as a loan in Euros, which the borrower changes into Rands.