Do all credit card companies charge to full months interest if you slightly underpay all owed?

User_101122

Give them a ring and just explain what’s happened.
I think maybe if you just explain it is a one off, you’ve always paid in full on time and point out how much or a valuable customer you are without sounding threatening.  You have a good chance of getting them to waive the interest as a gesture of good will.
Even though it is your mistake, it’s clearly obvious what’s happened and I can’t see them wanting to lose a good customer over it.