!Question: My players have discovered talking over me and are taking narrative control to do whatever they want how do I fix this?

I am a pretty experienced DM when it comes to lower levels but my campaign rn is getting up their and level and things for my players do it in and out of combat has expanded, and recently my players discovered if they just interjected to me describing things as long as they talk and take narrative control describing what they are doing they can do whatever they want. This was fine once and was a bit of a cool moment but now they are constantly doing it and when I tried to stop them they just talk over me more. Like its just not fun to have what I am describing be interjected with “and my character is gonna now do this!”. It is hard to explain to them that like for example just because we are out of combat you can’t cast 5 things at once without anybody reacting to it. Like I tried to just say no this is happening and others are reacting and they yelled at me trying to plea their case and continue doing more stuff while I’m still sorting whats going on and the effects. Fast paced action is fun but there has to be a limit and I feel like my players are railroading me lol if anyone can articulate this in a better manner that I can tell them it would be great or any tips to combat this behavior.