Interesting, because I haven't had quite the same luck with GSP when a seller, from whom I bought two items, inadvertently switched the shipping labels. I gave up in the end, talking to eBay I find is typically a fruitless journey other than to waste your time and raise your blood pressure to Chernobyl proportions. I received one item but not the other, but because the seller had switched labels, the item was shown as shipped.
Anyway, I hadn't realised that GSP has its own insurance, or that they repackage items.
As a matter of interest, assuming you're purchasing on behalf of a company, how do you deal with reclaiming the VAT on GSP items? I just get a separate Pitney Bowes bill, but it's not a VAT invoice.