Would you pay the postage if not expecting the charge

I had expected to pick up a prescription at the pharmacy, but instead they sent it to my house. On the invoice, they charged me postage.

Would you send them the originally agreed amount, less postage, or the full bill?

Thanks!

Sounds like a miscommunication- I'd call them and ask to have my account adjusted before just sending a lesser payment that might make your account appear delinquent. But if it's a tiny amount, it might not even be worth the trouble.