DearMr.Hunnicutt,
Iamwritingtoapologizefortheincorrectinvoiceyoureceivedfromus.Owingtoabreakdownincommunications,wedidnotcredityouwitha10%discount,asagreed.
Weshallsendyouthecorrectinvoiceassoonaspossibleandmakesurethatsuchamistakewillnotoccuragain.Pleaseacceptmyapologiesforanyinconveniencewehavecaused.
Yoursincerely,
PeterGibson