Honestly i already check his imei what he given to me.. the imei and the phone is blocklisted and looks like that iphone is lost or or stolen..
We have still no solution for this issue's unless if this iphone is clean we can remove that icloud not instantly it takes 3 to 7 business days. to remove the icloud..
Saying the truth I have researched a bit on the interent and I have found that the iphones that have icloud locked and are listed as blacklisted can be used only for parts.
OP what are you going to do with your iPhone, since you can't get back your money I think the last option is to sell it for parts.