Infinite Product Options

I used the app to try buy 3 item for x price but when you connect dropdown options to product ,at the checkout it charges your 3 item from dropdown list + actual 3 product's price.It means choose 3 item for£50 then at the checkout £50 plus your 3 items shows individually to customer total £100.Spoke to customer service they couldnt fix issue.They said dont connect products to dropdown text so if products not connect to text how I will track my stock?Whats the point of this app if you cant connect actual products to your option text?