USPS Short Paid Fees - how to dispute?

[ekbforays]

I'm being charged USPS Short Paid Fees multiple times for the same shipment and I think they're invalid in the first place.  Weight and Dimensions were not even near a cut-off point and it shipped Priority Mail.  How do I dispute this so I can find out what's going on and get a refund?  Post Office was no help - they have no idea how it works with eBay.  They did confirm my weight was correct.

[rfmtm]

Since you are having multiple issues, before you dispute, lets see if we can figure out what may have gone wrong.

What was the weight and dimensions of the package?

What was the to/from Zip Codes?

[ekbforays]

Someone from eBay contacted me and they said it was because my post office is in a different zip code than my return address, so they went in and changed the zone to further one and charged me the difference.  I am unable to find out why they charged me twice.

I have an email out to USPS and a reply to the eBay person who has access to the data to try to find out what's happening.

Weight and dimensions were not near any cut-offs.  Priority mail.

[rfmtm]

@ekbforays  When you ship you have two Zip Codes, one is your Return address Zip Code, and one is the  Origination or Ship From Zip Code, which is the post office it is mailed from that determines costs to the buyer's To Zip Code.

Normally your Return and Origination (From) Zip Codes are the same, but if you drop your package off at another post office in another Zone with a different Zip Code the postage would be calculated differently.

Next time you create a shipping label, click on edit next to your Return address at the upper right, you will see both your Return and Origination (From) codes and can change them if needed.  This change will stick for future labels.