Fairly standard. Not sure the app/infrastructure is really setup for foreign interaction to be honest. You're getting a lot of automatic responses here so I'm not sure anyone has actually "received" your complaint.
If they do, I don't think they're likely to call an overseas number.
If you're seeking a refund, usually this is all just done automatically via their system as opposed to speaking to anyone directly.
If it's for 50 RMB or so, I'd honestly just write-it off as a lesson learned. My rule is if it's under 100 RMB, my time is usually worth more than organising a courier to come to my door and collect an item and return it or whatever. I don't have time for that.