If you become my girlfriend, i will get you one for free.
Jokes aside, yes, understandable for those whom bought it recently. Coz i faced this situation before.  
Money went down to the drain.
No. Because sony uses different chipset for their phones, each chipset has their own fast charging technology. If Qualcomm, use QC. If Mediatek, use Pump Express.

Because their Exynos chipset is based on Qualcomm's quick charging technology, so it's compatible vice versa.