A check for ZDF
When looking up a show, record whether it is on the main ZDF channel, another ZDF network or the broadcaster's on-demand service. Compare the exact episode and time before claiming a station or app is missing it.
Check the station edition
Record one programme and its scheduled local time on the broadcaster page. Compare it with the channel label and time displayed in your player.
Check the guide if the live feed works
If the programme matches the live edition but the guide is wrong, confirm the channel mapping before changing the device clock.