If the landlord has strong evidence to suggest that the allegations were made maliciously, as opposed to them not being able to substantiate the allegations, then yes they should take some. That action does have to be justified and proportionate. A warning letter or acceptable behaviour agreement/contract might be appropriate depending on the circumstances. Here is an example of where this has been done. Whilst investigating a stage 2 complaint that the landlord had failed to deal with allegations of ASB appropriately, the complainant put forward the names of several neighbours who could apparently verify the incidents of ASB by another neighbour. When the neighbours were interviewed they all stated separately that they had previously been bullied by the complainant to make false allegations against the alleged perpetrator. Furthermore they disclosed that the complainant was spreading malicious rumours on the Estate about the alleged perpetrator. The complainant was given a final written warning. You do not say what the landlord reported the vehicle for. Generally speaking there is nothing to prevent a landlord (or anyone else)reporting a vehicle to the relevant authorities if they believe a law has been breached.