iPhone 13 return

[Heavy]

I upgraded my iPhone 13 to a iPhone 15 pro.
When I returned the iPhone 13 I forgot to do a factory reset. A few days later I received an email telling me to provide my phone unlock code or my Apple ID. I replyed with both. Now 2 months later I received an email stating I am being billed for the upfront edge amount for the iPhone 13. Does anyone know who I contact to straighten this out.

***Edited Labels***

[RogersZia]

Hi @Heavy,

Welcome to the Community!

This is an odd one, I am not quite sure we ask for Apple ID passwords in case a customer doesn't factory reset their phone. Would it be possible for you to share a screenshot of this email? (Please make sure you blank out any personal info). 

I assume you received a return kit and used that to send back the device? We can definitely look into your account to see what's going on.

Let us know if you still require help with this!

RogersZia