Poor online book delivery

I ordered a book (that showed in stock) on the 4th of May, and it said the delivery date would be the 1st of June. It has been 17 days since then and I'm still waiting. I have phoned several times, and every time they have the excuse "the shipment will arrive in a few days". They also ask if they should phone back with the update on the shipment, but they never call back. I'm highly disappointed in this service.