Interesting to note that the CDU stepped in to complain and accusing the German press of forming a cartel!!!!!
The CSU isn't the CDU, they are sister parties - and the CSU is only active in Bavaria. For instance, the CSU's Transport Minister was the one demanding the PKW-Maut which the CDU was against - but the CSU demanded it as a condition of entering the coalition. The CSU is much more socially and financially conservative than the CDU.
Something does not add up here
You need to know that there's no Federal broadcaster in Germany. Broadcasting is constitutionally a matter for the individual states, and ZDF is a channel created as an alliance between the individual state broadcasting companies. Hence the comments about a "cartel", because the CSU is suggesting that ZDF is controlled by rival political elements that hushed up the news.