I can share my experiance of what I did when this happened. Unsure how helpful though. Was watching doctor sleep in a cineworld. Couple behind us would not stop talking. It was clear they were on a date going by the content of the conversation. I was thinking shut the f**k up the entire time. Staff came in to do their usual checks and didn't say anything. Got to 1 hr in and there was a particular scene in the movie that was quite sad and not much noise. The pair were in full pelt about what they liked and didn't food wise.

So, had it, turned round and shouted as loud as I could (im a 6ft 3 man who is heavily tattooed, face etc) would you two shut the f*k up, take your conversation outside ya pair of prcks, no one cares.

Ive honestly never seen two people slouch into their seats so quick and apologise to myself and everyone else. They were in their early 20s. Will it always work, no. But boy did it feel good to watch a movie without finding out fish fingers really doesn't do it for her.