Kitchen overdue by 31 days

On 21 August 2015 we paid our deposit in full. The contract stated that the kitchen will be installed with in a period of 15 days after the deposit was paid. It is now 31 days later and the kitchen is still not usable. We are at the end of our rope. What do we do from here. Do we go to the ombudsman? We tried being nice and allow extra time. We even went as far as a legal letter. All we want is a finished and useable kitchen of a good standard and quality.