How do a I arrange a return sendle connote for something?

Needing help to raise a return lable through Sendle 
I had 2 lots of clothes sold on the same day and wasn't able to print the label, so took it to our closest sendle location where they printed the labels, I cross checked the details and package and the lady attached the connote to the wrong packages! 

Now I'm needing to raise a connote to send the clothing to the correct buyer 

Any ideas how to do this?