delivery is a mess

I'm very disappointed and frustrated at the fact that I have paid and now they are not able to deliver my order. Why did they take my order knowing very well they won't be able to deliver it at my address. why can't they change the courier they are using now. They were able to deliver before, what changed. 3 courier guys already called, and 2 customer consultants, but still no progress on the matter. I need items by asap. This is such an inconvenience,