... I'm not from a country where suing people is a common occurrence but usually the way you fix is through the beauracracy. With a few sensible steps to shortcut the process.
You call/email/talk to people until you find someone that has any measure of power, and escalate to management as necessary.
If you have a bill that is "signed" by the manager of some collections department etc of the company (even though it would have been processed by some underling), you politely request that person's phone number and establish a one-to-one dialog, explaining calmly that it's clearly a mistake and that you expect the charges to be reversed and a full explanation of what has happened.
If you have a name of someone who is, or should be, responsible within the company, you can often infer an email address. Firstname.firstname.lastname@example.org or some such. If you have one person's email, you can infer another's.
Phone and-or email at least weekly. Ideally keep a polite, calm,reasonable email paper trail, copy in anyone you've talked to along the way. Don't get angry but do insist that it's clearly a mistake, that you expect someone to take responsibility and that you expect the charges to be reversed.
The biggest surprise, as with so many news stories, is that it became a news story at all. If you are a squeaky enough wheel, you basically become someone's full-time job to figure out some kind of solution.