I buy from them all the time and they cant even allow one delivery for multiple orders going to the same place

I bought solar lights, and then realised I should have increased the quantity because I wanted x4 of the lights, so I had to make two orders for the same lights coming to the same adress, when I asked if I could get charged one delivery fee for the shipment I was told that they cannot do this, I buy from them all the time, yet they cannot even allow this.