Missing cushion on brand new lounge suite

I purchased a lounge suite in store on the 4th August, paid cash in full. On the 7th August it was delivered however I was not home and did not open it. On the 8th August we opened it to discover one of the cushions was missing. I immediately reported it to the store consultant. She has been extremely helpful to try and get this sorted but unfortunately at this point on the 26th August we are no closer to having a resolution. We have been told a whole new lounge suite will be brought (just to replace the missing cushion) but even with that there just seems to be no progress. This needs to be sorted out immediately