Intuit PaymentNetwork will be discontinued on 5/31/2016.
Learn more about the transistion.
This article provides information about how to sign in to the Merchant Service Center. It also includes:
For Payment support, to increase your limit and review your account profile for credit card or check processing, go to the Merchant Service Center.
To manage similar information for online invoice payments, go to Intuit PaymentNetwork.
MSC sign-in page:
PaymentNetwork landing page: