Apple's DND MODE can't stop messenger CALLS!!

It's a shame how apple is failing to stop an app to invade our private space/times, I have set bedtime mode in my iphone so I can get proper sleep. It's very importantant for my health, yet people from messenger can call me as they wish, even in the DND MODE it happens. Now sometimes it's not possible to turn off WiFi and even though I have stoped every notification from messenger, the calls are still coming. I wish apple had gave us something so we could feel in control. The focus modes should be much more stronger to help us focus in our work.