can you change the item in a transaction

[#1]

A user charged something incorrectly.  The dollar amount was fine, but the item was not.  Is there a way to change the item in a transaction?

[#2]

I had a similar issue- A customer placed an order, and luckily they left a note- they ordered the wrong item, but the price was the same.

I now have to contact them manually to let them know I corrected it.

I also now have to manually update my inventory.

This should be an easy thing to edit items being shipped:

2 of this, X this. Add this.