@reallynicestamps
The surprise customs charges are related to the eBay's other program. eBay's Standard Intl Delivery. Shipment starts off with USPS gets handed off to PB who hands it off to DHL's ecommerce division(There may be others involved but that is the only one I've had dealings with) who either does final delivery or it gets handed back to Canadapost for final delivery. If it does get delivered by DHL any customs/duties & taxes need to be paid prior to delivery. Once it's in the ecommerce division tracking system it's a bit of process to locate the tracking details.
I have heard of those situations you mentioned where the seller ships without using GSP and buyer ends up getting billed customs. That's just another unexpected schmozzle that a buyer has to make sense of and the hoops they need to jump through to get any money back they are owed.
-Lotz
