Will social networks help management to cut down the cost of customer service?

Of course it has also lowered the number of employees in the company ...dispense with intermediaries leading to reduced production and distribution costs

it depends on your business model, let's assume your business have two sides (offline customer service/ feedback and online customer service/ feedback social networks help management in different angels, but you should know the psychology of your customer ( customer behavior ) maybe your customer behavior on the internet is different compared to the reality.
so you will have wrong feedback / analysis.
then if you don't have real feedback, your process is in dangerous.
what am trying to say is social networks help us in our business but don't take it as a basic.
and remember one of the Ps in the Marketing is physical evidence.

Social media is more complex than just saving costs.
It carries risks and issues.
One of the biggest risks is if you do not engage your customers through social media.
They are Twittering, Facebooking and generally talking about you.
Your whole customer service effort can be undermined if a social media disaster occurs and you do not have a ready response.
If you have a good channel to handle online queries - yes it can be cost-effective.
If you use it to get a better handle on customer wishes through active monitoring, it can be very cost effective in marketing research.
However, you must have a clear social media policy, and properly trained team.
Any mistakes are in public, not a phone conversation between two people.
Plan properly.