I think I disagree with the posters in this thread who suggest this is nothing to worry about simply because the error was promptly fixed. If it happened to the OP, it is undoubtedly happening to other customers. Most will notice and question it and have it manually corrected, and credit to Full Flavour for the quick and helpful response in this thread, but some might not. Life is busy and I'm sure I'm not the only one who doesn't always open monthly invoices for utilities set up for autopayment. If this error is happening due to a shortcoming in Xero's billing software, Full Flavour should withdraw the ability to prepay for a year until it's fixed. It's not acceptable to overcharge until challenged on it, it simply shouldn't be happening in the first place.