I think any sort of prolonged noise or disturbance like that should be addressed by the CC . Doing nothing isn't acceptable. I would have asked to speak to the CSM / CSD on the basis that the CC were not dealing with the issue, and I would definitely follow up with Customer Relations as well.

I had a similar type of incident on a long haul flight where we were on the UD and were constantly being "invaded" by people from downstairs visiting their friends, drinking, swearing (the language was obscene) and generally creating a lot of noise, a nuisance and a general disturbance. The CC on the upper deck (one of whom was on her first flight, and the other who had only 6 months in the job) were ineffective and basically ignored the problem. It is probably only the second time I had a DYKWIA moment on a plane and stomped downstairs to find the CSM. The only way they could get the passengers back in their seats in their correct cabin was to have the seatbelt sign switched on.

The CSM was extremely apologetic and boarders were repelled and sent back downstairs from that point on, but the whole episode was unnecessary and should have been nipped in the bud from the outset.