Does anyone here have experience purchasing goods in an EU/Euro using nation AND used Global Blue for their tax refund?

I ended up purchasing a new watch for about $10,000 while I was in Paris, and I submitted my global blue paperwork from here in the States back to Europe on 1/6/15. I used the Global Blue labeled envelope that I was given by the shop owner, and it was addressed to Global Blue's office in Slovakia. At the airport before I left Paris, I tried scanning my paperwork on the PABLO machine, but it would not scan. According to the tenant who was at the machines, I was forwarded along to the next line where two officers operated a desk. I showed them my paperwork and explained my issue, and they placed my paperwork in a machine and stamped the copies I returned to Global Blue. I'm assuming this was the customs stamp.

According to some things I have read (and what I assumed at time of purchase), the commission that Global Blue takes is the difference between the VAT and the return that is listed on the tax paperwork. On the watch I purchased, the refund was 12%, so GB's commission is 8% since the VAT is 20%. Why are there people out there receiving less than 12%??

For instance, my sister was with me on my trip and she ended up purchasing a scarf for about $304 U.S, or $250 Euro at the time of purchase with a 1.21 exchange rate. She just received her refund back, and it was only $29. That's a bit less than the 12% we were promised even with the further weakening of the Euro to 1.15.

Does anyone else have any experience with Global Blue purchasing goods overseas, and not receiving the proper amount back? Today is 1/20/15, and I still haven't seen my refund hit my AMEX, but my sister received hers back on 1/15/14.