How difficult can it be to change an order

I battled to place my order on the website but eventually managed to place my order, today I called to change the delivery person, address and date. this should be allowed as I am the client. after being on hold for what seemed like forever I eventually got through to an agent, sadly I did not ask her name, but she seemed so shocked that I wanted to make so many changes then after giving her the details I was put on hold for such a long time that I almost disconnected the call as I have other work to do. then when I wanted to give her a new contact number she was out rightly irritable with me and put me on hold again for forever. if this is the service they give I wont be ordering from them again.