Only enclosed half the order

[fi_6135]

A buyer bought 2 items I was selling.  I didn’t realise it was one buyer until after I had sent one item. Now I have no way of sending the second item which should have been in the parcel.  How do I send second item to them as I cannot reuse the label a second time?  Do I just have to refund them? 

[john1297576]

Bought two items, each would need a label, so why not use second label.

 combining has not been possible for weeks so each sale is a seperate item.