I know that most programs here in the states are a specific length. Not sure if it is the same over there but most likely is. They have to have something fill the gap and if nobody is advertising then that is what you get stuck with as they aren't going to give more airtime than what is in the contract for a specific add. Otherwise the TV/Radio schedule would start to get off and you would find out that favorite show you want to watch came on an hour early.

I know how annoying it is for us to have the emergency broadcast tests every week or so. They used to do them in the middle of the night but now are required to do them during the day, mostly prime time.

Give it some time and everything will go back to normal. I always find the mute button my friend in times like yours.