iPhone 6s battery replacement

I bought iPhone 6s at Astana in Kazakhstan September 2015 at the beginning evertthing was perfect half an year later shutting down and restarting again shutting down problems started finally Apple accept this failure and opened chargeloss replacement battery I want to utilize about this option.

First I checked my telephone ID by safari page (pls.see attachments)than I contact Apple support and I followed procuderu what they informed me.Apple support had got appointment for me by the service (name is PUPA)12.01.2019 at 15:00 oclock I was there and they checked accepted my phone battery will be changed regarding REP until now all was ok but after 3 days I ve got sms by service it was writing waiting for prepayment.I went there and spoke with them whats happenning 3 days ago no bodies told me replacement will be charged now you informed this.They told I should pay because costless replacement battery is over.Again I called Apple support service again the same procedures followed to gave them my iPhone id etc etc finally he aggree about free of charge battery replacement and send me other Apple service in İzmir (service name is EGEMAK) again they told me the same as first service again I called Apple support service her name is Özge and she said she is senior person she gave me opposite information who gave me at the beginning by Apple support service

If I summarize to bought apple product is regret because responsible persons from Apple has no information about this issue