It appears that Shopping Cart Creator Pro has a major flaw!

A buyer can process an order without selecting shipping destination which means that they do not pay any tax and can check out. I have been advised by CC that their software does not have the facility to stop a buyer from completing with a transaction without selecting the shipping destination. So the buyer orders goods without paying any TAX!!!
I am told that I can edit a php file to add a comment at checkout to alert the buyer that they need to select shipping destination, but surprise surprise, CC can't assist me. Is there anyone that encountered this problem before and can advise.