Shortage on calculated shipping

[johneezstore]

I use calculated shipping for most of my orders.  I sent an invoice that charges $11.78 for FedEx Smart Post.  I go to print the label and it charges me $14.14.  When I call customer service she tells me the rates are only an estimate and are not exact.  She then tells me I need to call FedEx to complain.  I've been doing this 20 years.  I hope this isn't the way the future with eBay is going.    I just hung up and used a Med FRB with USPS for $12.42.