Provider has the subscription ID, however no subscription can be found on neither on POA side nor on PBA side by searching in the Subscriptions list.
How to obtain subscription details like Account it belonged to and the reason of subscription removing?
The subscription information can be obtained in the PBA-E event log:
Home - Operations - Tasks - All Events tab.
Subscription ID should be entered in the Parameters field.
Most probably it will be possible to locate events that have some Order ID as the parameter, like this:
49318425 Cancellation Order Cancelled SubscrID=1022637; OrderID=909190; Descr=Cancellation Order Cancelled;
Searching for the Order ID in Home - Operations - Orders - All Orders for the obtained Order ID, it will be possible to locate the Vendor, Account and other related information.