Fixing a tint film onto car windows

Some time in March, I decided to fix a tint film onto my car side and rear window (not the front) as I was told that this reduces heat in the car. In fact, the difference is felt. The car is definitely cooler inside, especially in summer...

After a few months I discovered that applying tint film onto car windows is illegal. I was fined twice. The traffic police informed me that in Malta (unlike the rest of Europe) there is a law prohibiting tint film; however, the retailer is telling me otherwise.

If this service is illegal, how come the car accessories retailer is allowed to offer this illegal service to the detriment of consumers?

To what extent do traffic officials have the right to tell drivers that it's not their business if the retailer is offering an illegal service?

To what extent is the police empowered to fine offenders if they acted in good faith on having bought a service from a lawful establishment?

Who is right and who is wrong? Is it the car owner who ended up paying for the service as well as paying the fines? What protection do our laws offer to these bona fide car owners like myself? (Pierre Sammut)

I asked Police Superintendent Peter Paul Zammit, from the Prosecutions Unit, for his comments on this matter:

The legal situation is that the offence is one of having carried out alterations to the vehicle without the necessary permit. As you are probably aware, there are degrees and degrees of visibility and, at the present stage, the Transport Authority (ADT) has set in motion two mechanisms, one wherein in the absence of legal parameters of visibility they have set administrative parameters and the other is that they have prepared (in the final stages) a legal notice to clarify the issue.

I hope this clears up your query. If you need further clarifications do not hesitate to contact me.

I thank Superintendent Zammit for his co-operation and for offering further clarification if needed.