Advertising Agencies are about building and reviving growing brands. They make the advert possible and develop the companies ideas and provide filming equipment and qualifed cast.
Enginegroup (http://www.enginegroup.com/) has worked on adverts for companies like:
E.ON, Santander, Sky and many others.
Here is an example of one of their adverts:
This was an advert for ‘Betfair’ wherein they use comedy to attract an audience.