How do I make a claim?

I paid for cinema tickets 2 days ago.
On the screen, there was a big dent.
I was really unhappy.
Afterwards, I spoke to a manager and told him about the problem.
I took him to the screen to show the problem + other film goers while there said they had seen the fault (which they also explicitly said spoiled the whole experience.)

Manager took down my contact details and promised he would call back.
I took down managers name - he handwrote on a piece of paper.

No call from them. :frowning:

Really not happy. How do I make a claim for the payment?