changing delivery dates with no notice

Why would you make a delivery date when you just go ahead and change it without notifying your customers????? This is now the 3rd time that I have been promised a certain order and then without notice the date is changed and when I call the call center I get told that your system says the new date and there is nothing they can do to help and bassically I am made out to be a **** !!!! I received an sms yesterday confirming my order would be delivered today, I then received a further sms this morning confirming the delivery of my order . Now I just received a message my order is now coming tomorrow. Surely if it was promised to me today I should receive it today ???? Or wouldn't the decent thing to do is contact the customer and let them know that there is a problem and would it be ok to move the delivery date ???? This is honestly pathetic !!!!! You lack service s****s and your consultants are extremely unhelpful the only way a problem is ever solved is when a customer waits on hold for ages and then lets the manager have it !!!!!