Sent an iPhone 11 Pro with a faulty battery?

[Af1964]

I recieved my refurbished iPhone 11 Pro on 16th April 2021, and the overall battery health arrived at only 90%, and has since gone down to 85% after just over a month - a 5% decrease in a month! 

According to Apple's website:

A normal battery is designed to retain up to 80% of its original capacity at 500 complete charge cycles

My phone has had 367 complete charge cycles and is on 85%, so in the month I have had it I have not charged it 367 times! EE states:

All refurbished devices are repaired to the same grade as our Good as New devices

Now I would assume that Refurbished and Good as New phones would have new, serviced batteries at 100% or more overall health (some new batteries show overall health over 100%)

I spoke to an EE agent via live chat who advised me my phone was under manufactruer warranty, which it isn't, and to cancel my contract and to reorder a new phone which I did not want to do since the battery clearly needs a replacement and Apple will not cover it, am I eligible for a repair since the device clearly has a faulty battery? 

Any help would be appreciated! 

[Chris_B]

@Af1964   According to Apple website.  That’s provided the device has been looked and has been kept in perfect conditions.    
  
 Refurbish devices might not get a new battery unless stated.  
 
 If the device is under warranty as the agent claimed is then you can send the device off to EE and allow them to sort out the battery for it.   But as the battery isn’t below 80%  I’ll be very surprised if they change it,  if the battery was at or below 80% then I believe they would as below 80% the battery is past its optimal performance level and will need to be replaced.   

[Af1964]

Well in that case I’ll wait another month till it drops down to 80 then get it fixed! Still seems to be degrading extremely fast. -5% of its entire health over the course of a month with regular use, charging at night with optimised battery charging on, with an Apple-manufactured charger.