I returned an item of clothing and still haven't been paid back - should I sue them?

Yes! Sue them for a billion dollars! And to be CEO! And also for a superpower like laser eyes or invisibility!

Call them and ask them what the situation is.

I think you should kill them.

Call your credit card company and have them reverse the charge. Another thing to do is to check Better Business Bureau to see if they have a good reputation, and if they do, file a complaint there, they will be forced to deal with it pronto.

I would be making a complaint

online?