The order won’t actually matter here - but even if it did, the “right” thing will happen either way depending on which interpretation of the email you have.
The third transaction got the same response as the second. Which would actually imply that the common reading of that email (he’s getting $25 back from the second deposit is correct, and he’s going to get the entire $9,975 back from the third.)
totalReceived = totalReceived + transactionAmount
if (totalReceived > 10000) {
sendEmail()
wait10weeks()
refund(transactionAmount)
totalReceived = totalReceived - transactionAmount
} else {
buybonds(transactionAmount)
}
A horrible way to write a system of course but if the system takes 10 weeks to process a refund then it doesn't sound like the system is that great to begin with