You are receiving this error because you have made more than 100 successful login requests in a minute. In the event of a breach of the login limit the account will be prevented from creating new login session for a 20 minute period.
The error TEMPORARY_BAN_TOO_MANY_REQUESTS will be returned in these circumstances. All existing sessions will continue to be valid.
Please note that if you attempting to login to the Betfair website while this restriction is in place you'll receive a dialogue box stating the following:
"This account has been locked because our systems have detected unusual traffic from your computer network. This is a security precaution. Please try again later or contact us if you require any further assistance"