It sounds like she misunderstood that your 500 miler e-upgrades were deducted by mistake since you already had an SWU valid for all of the segments from BKK to STL.

Therefore, I think she gave you 16 500-milers because she thought an e-SWU was deducted... ?


------------------
Thank you for flying and staying UNITED. Your business and support is highly appreciated. Enjoy your flight and spread the word!