I just want to share something with you in case you ever need to use it, or a variation on it.
I ordered 50 of an item from a Chinese seller on eBay, paid by Paypal.
The package arrived, with the envelope intact, but the inner bag ripped open. Instead of 50 there were 30.
I reported this to the seller, who offered to send me 20 more to put it right.
The problem there, is that if they renege on this offer, too much time will have passed for me to a) make a claim against them on Paypal, and b) leave a negative feedback.
But I refuse to punish an honest seller by doing either within the time limit, only to receive the goods later.
My solution, was to order another 50, asking them to add the 20 owed to me in the same package, and ensure I received a total of 70. This way they are not out anything on the shipping, if it was an error by a staff member, and the time clock starts again. If the extra items owed to me are not in with the second order, I have the conversation on record.
There is always a solution that is ethical and fair, while protecting both parties, you just have to figure it out.