It's sad to say buy : eBay won't care about GSP bugs.
They have a partnership with Pitney Bowes and with GSP program, everyone is happy.
By everyone, I mean : eBay, Pitney Bowes and the seller
The buyer is not important enough, since he pays the bill, everything is "ok"
It's been few years that people here are raising flags about multiples problems on the GSP program and nothing changes.