Where I work, we have an in-house debt collection group and a third party one. One lot gets the high value (£500+) the other the low value. A basic system error such as the address changing on the system randomly (happens a lot) can mean a warrant can be issued over an amount lets say £200 - a quarter or two of usage of energy. The person didn't pay the bill because they never got it, nor did they pay the further 8 reminders/warrant letters that they received, because they didn't receive them. They were returned to sender and shredded.
I can fix this by checking the previous bills that were paid - takes 10 seconds, calling the number (if available, usually good customers have this available) and just checking or using our in-house database. Often 10+ people have checked the account for all the legal stuff of getting the money back and not one did the simple checks I do.
Outcome? I am too embarassed to call the customer, I amend the address and resend the bill, I put sarcastic comments in the contact history and expect that the bill is paid a week later. I expect they get credit problems, I try to address this issue with the bosses to no avail.
Another thing I love? People GUC - give up complete - their accounts and move out, no forwarding address given and their number on the account goes to VM - i.e. dead phone. SO what do credit management do? Send out 10 letters over a few months about how they are going to recoup the debt (of the previous occupier) - ****ing great, what will that achieve?
You like so many of the people I deal with have done NOTHING wrong yet it goes so wrong.