We are continuing to work on ongoing Sandbox issues. Currently the CustomerManagement service is not available, which means that the GetAccounts and CustomerSignup methods are not available. If you attempt to make a call to GetAccounts, you will receive "Unauthorized Access".
We hope to have this resolved soon, and apologies for the inconvenience. This only applies to the Sandbox environment, the Production environment is not affected.
Jeff Dillon, API SUpport