The mid-market exchange rate moves throughout the day based on global currency markets, so a quote from yesterday will rarely match one from today — that part is outside anyone's control.
What should not change is our margin on top of that rate. If you believe the margin itself is different from what's listed on the rates page, contact us — that would be an error worth investigating.
Scheduled or repeat transfers lock in a rate at the time they're set up, and we'll email you if the underlying rate moves significantly before the send date.