Hi,
Are you running any other API application or indeed another instance of Betting Assistant at the same time? If so you would need to adjust the throttling accordingly so that the combined data requests do not exceed 20 per second.
Also using the Betfair website at the same time will be using data requests.
If you email
bdp@betfair.com they should be able to give you a breakdown of the data requests which should shed some light on where you went over.
If this is your first time for incurring the charge they will usually waive the charge.
Regards,
Mark