Following this because I am in the same place and have no idea what to ask at the appointment.

I would stop trying to convey how bad it is and start saying what you want them to do. Not on gym and peptides but the pattern is familiar.

Do you contact the customs office or the carrier first?

Same shape here, different drug. The thing that helped was documenting the refusal rather than re-arguing it. They refer rather than write.

I would stop trying to convey how bad it is and start saying what you want them to do.