1. Check whether an additional shipping charge is set up for your products.
   1. In the administration panel, go to Products > Products.
   2. Open the details page of the product for which the shipping  cost is displayed incorrectly by clicking on it's name or the button  with the cogwheel icon and choosing Edit.
   3. Open the Shipping Properties tab and check the Shipping freight ($): option. If you would not like that the additional cost is added to the  shipping cost for this product, the input field of this option should be empty. In this way enter 0 and click on the Save button.
2. If a realtime shipping method is set up, check whether an additional charge is set up for it.
   1. In the administration panel, go to Administration > Shipping&Taxes > Shipping Methods.
   2. Click on the name of the real time shipping method.
   3. Open the Shipping charges tab, check whether rates are set up in the Cost dependences, Weight dependences and Items dependences sections there. If any rates are set up there, they will be added to  the shipping cost which will be transferred from the website of a real  time shipping service (for instance UPS, USPS, etc.) If you would not  like to add the rates to the shipping cost, remove them and click the Save button.