How to request refund when subscription isn't showing, with no access to iPhone.

Hi,

I'm trying to cancel a subscription to an app and request a refund (Renewed today).

Due to an extremely over complex process of trying to gain access to my own apple account so I can cancel, I couldn't cancel in time - and so I am here.

I've done everything suggested everywhere I can find:

1. On "Report A Problem" the subscription isn't showing - dead end.
2. On iMac app store, subscription can only be (and has been) canceled, no buttons to refund/'report' (1).
3. Request refund from app developer (they suggested I try 1 and 2)
4. Check receipt, and 'report a problem'. Never received receipt from apple, only PayPal - no button.

I don't have access to the iPhone on which I originally purchased the app, and I cannot seem to log into apple music via my Android phone. The verification code to log into my account isn't being sent to my trusted number..

I feel like I've completely missed something, because no way should it be this difficult to get my money back..

Many thanks,

C.