Un taxed cars parked on street

We have a garage on the next street and they continue to leave cars on the street for days and weeks at a time. Some even have flat tires as they have been parked so long. They are using the street to park cars from their business.

My understanding of the law is that a car cannot be left on a public road if it has no MOT and tax? We currently have 6 cars with no tax or MOT on the street,

This issue has been reported to the local council on numerous occasions, but nothing seems to be getting done about it. This has become very frustrating for the residents on the street as often we have to park elsewhere.