When you are dealing with an unsatisfied customer there might be a long list of things you cannot do for them that they wish you could.
But if you are truly wanting to serve the customer, dig deep and find the one or two things that you CAN do on their behalf.
See if you can’t connect them with someone who can help them.
The idea is to say:
“Sorry unfortunately I can’t help, but I know someone who can, let me connect the two of you, I wish all the best.”
If you don’t have someone to connect them with, share advice of where they can look for help.
A helpful hand is always welcome even if it does not bring with it everything they hoped for.