When is it necessary to escalate customer problems to the manager?

Depends on the problem, is it urgent? does the customer have a valid point of view, do you have the authority?

Most complaints are general and not realistic, you should use you personal judgment and try to wear the customer hat to understand their way of thinking.

Customer problems should have traffic lights formula.. Yellow  48 hours , Green  hours and Red  WEEK

Green is ideal to escalate .