Rand transaction in South Africa becomes a US dollar one on my account

<p>I did a transaction in South Africa, using my South African card. The transaction was registered as a dollar transaction on my account. I don't understand how a Rand transaction in South Africa processed using a South African POS was placed on my account. What also doesn't go down well is that this is a foreign currency going off my account. What was the exchange rate on the day and why was it processed in Rands. Investec said this is your doing and not thiers. Please advise urgently.</p>