Yes. They regulate things like this. It used to be the ITC then OFCOM and now them.
If you do make a complaint, the channel has to provide a copy of the output at the time (they are required to keep recordings for 60 days), so that the ASA technical people can measure sound levels.
A few channels have been done for this.
Though you have to have exact times/programmes rather than just a general "ads seem louder on Sky 1" or whatever.