Advertising is up, but it is digital
Richard Harman at Politik has this summary of data from the ASA

So the advertising spend has increased a healthy 30% in five years. But the proportion spent on digital advertising has gone from 6% to 60%. With this change, radio has held up very well as an advertising medium, but TV, newspapers and magazines have plummeted.
The solution here is not a government law change. It is a shift in business models.