Decofurn Factory Shop's Breach of Contract

I bought a bed and a chest of drawers online for +R7000 from Decofurn Factory and was advised that it would be delivered free within 10 days to the address I provided in Mbuqe Extension (Mthatha).

Shockingly, Decofurn has emailed me that they "do not deliver to township/location or farm" and Mbuqe Extension is neither of these.

So I wrote back that Mbuqe Extension is one of Mthatha's suburbs and so what is Decofurn's challenge? Is it now suddenly classified as one of these due to its residents. All courier service providers, furniture shops within the area including postal service deliver door to door.

Why must the terms and conditions of sale be altered after the payment is made.

Cheated customer