I tried adding a courier's tracking details to a sale this morning.  The courier is APC.  I get a message saying that another seller has already used that tracking number so I'm unable to add it.  APC (and perhaps others) do re-use consignment numbers.  How can I add this to my sale to ensure I am compliant ?

I contacted customer services and was told that I need to contact the courier so they can "unlock" the tracking number.  This doesn't sound right to me.

Please advise.