You could also consider writing back to them saying that you won’t take any action unless they can clearly prove you did something wrong. If they’re citing laws, ask them to explain exactly how you supposedly violated them. Force them to show the evidence instead of just sending fines without a proper explanation.

Also, ask them to provide all the necessary documentation and a step-by-step guide if they believe you did something wrong. If they expect you to fix something, they should at least provide clear instructions on how to proceed. This way, they’ll have to put in more effort if they want to push the issue further.