Post office rejecting parcel after label was generated

[gart_1850]

I sold some Lego in its original box. When I took it to the post office.  They printed the label and then measured the parcel and said it was to big for the medium parcel. I took the parcel home. It looks like it has been shipped but has not.  What should I do? 

[**peaseblossom**]

If possible cancel/refund the transaction with the buyer's agreement (via the dropdown actions menu arrow for the item on your orders list) and relist with correct postage for the buyer to buy and pay again. 

Or you could buy and pay for the correct postage yourself.   Then change the tracking via the More Actions dropdown menu or View Order Details > Postage > Track Package > dropdown arrow.

@gart_1850