How long does it take you to develop a website?

Hi, Can anyone help me to know how long does it take to develop or rebuild this website to start selling online?
Because I’m sure something wrong with the developing company since they take more than a year just to add some new options to calculate delivery charges depends of the selected area, make integration with our oracle system to take prices and stock and add the payment gateways integrations!!! and they done some changes in the products images and layout.

Please advise me if I’m wrong or not? and how I can convince owners that something going wrong

Please not change the category title from General to anything else. You have a general question, therefore it belongs in the General category.

Thank you.