The items actually do not all fit into a 500g satchel hence why i am trying to put the clothes into 2 x 500 gram satchels (because i have two left over) & charging the buyer 13.40 because the items weigh MORE than 500  grams

If you have charged them $13.40 for postage, put them in a 3kg satchel with one postage label. If you've already printed a label for 500g, cancel it and print a new one.

The way your opening post read, it wasn't hard to jump to conclusions. It was worded like you were trying to send one for free. If you don't want people jumping to the wrong conclusion, word your posts better.

If you donht have any 3kg satchels and can't get hold of one, Then you can tape them together and process the label as a regular post parcel using weight and dimensions. Though itt is likely a 3kg satcel will be cheaper unless its local.

Are the satchels the eBay ones?

just a thought, but check with the Post Office first.

package the items into the 2 satchels, print a 3kg label, securely tape the parcels together so that only one label pocket is visible, and put the postage label in the pocket.

if you've already printed one eBay postage label, cancel it and re do the postage.

If the OP only has 500g sized satchels, and the garments will fit in it, could they turn it inside out and then stick the 3kg label on?