Why was my petrol payment deducted from my SGD wallet instead of my MYR wallet, even though I had enough funds in MYR?

Petrol station self-serve payments (with merchant category code MCC 5542) involve a two-step process: a pre-authorisation followed by a final charge.

Here's how it works:

1. Pre-authorisation – An amount (typically RM200) is temporarily held on your MYR wallet.
2. Final authorisation – After fuelling, the system attempts to deduct the actual amount from your MYR wallet. If there aren't sufficient funds at this point, the transaction is charged from your other wallets instead via SmartExchange™.
3. Reversal – The initial RM200 hold on your MYR wallet is then reversed.

You may refer to the example below:

You start with MYR 100.00 and SGD $202.88.

A RM200 pre-authorisation was attempted on the MYR wallet via SmartExchange™, but since there was insufficient MYR balance at that moment, SGD $59.92 was exchanged to cover it.

After fuelling, the final amount (RM31.20) was authorised.

Since there was still no MYR balance, a second SmartExchange™ occurred, converting SGD $9.35 for the final payment.

The initial RM200 hold was then reversed, as shown in the transaction history.

This is an expected behaviour due to how Petrol station self-serve payment transactions work and not an incorrect deduction.

Future Travel Tip: To avoid automatic currency exchanges and ensure your other wallet balances aren’t used, please make sure your MYR wallet has at least MYR 200 plus the value of the petrol you've pumped.