I get through all the same old fucking custy complaints by switching up my tactics to amuse myself.
One minute I am sickeningly sweet, and plaster a giant ass smile on my face. (I'm actually shooting them FUCKYOOOU vibes through my eyes.) If you go super over the top with sappy niceness and concern they usually get embarrassed and leave without too much further incident.
The next custy complaint, especially if I'm in a bad mood and the custy is being super stupid about a policy, I just keep repeating the policy/apology until they go away. Its so hilarious.
Make each custy encounter a new challenge to see if you can get them to leave in ten seconds or less!