Technically, each invoice already has an expected amount which the customer can only pay exactly as the invoice expected amount. When a customer proceeds to pay with a different amount (mismatch amount), the following will most likely happen:
- Payment unable to be proceed
- Payment will be failed
- Payment proceed however it is being reversed by the bank
The above conditions work for online payment methods. However, when a customer pays via RTGS/LLG or through a bank teller, there is a chance that the mismatch amount payment will still be able to go through as the banks do not conduct payment validation.
When such an incident happens, it will need further checks from our side as a mismatch amount will not automatically complete an invoice.