Should Windcave service be down, you will likely get a timeout error.
You can check the status of Windcave and subscribe to outage alerts at: https://status.windcave.com/
Should you get timeout errors, we do have a process that runs 4 times a day to check the Payment Txn in Salesforce with Windcave online. It is also a good idea for you to check Payment Txns in Salesforce status vs. the Status of the payment in Windcaves online portal (PayLine)