Excessively high water bill

Just received an excessive water bill (>$500) for a 2 person household, more than 4x the amount that we typically pay. I’ve submitted an adjustment form online. Just wanted to see if anyone has been able to get figure out what caused an unusual spike in their water bill and if they were able to either refund or resolve a bill? Additionally, our neighbor who we share a water meter reading with had an unusually high bill last month (>$800). We thought we were in the clear because ours last month was normal, but then got hit with this one today. Seems like it’s got to be something with our reading since both of us have gotten unusually high bills.