New Whiska's dry Cat food - not the same delicious taste or quality

Our " previous" cat - now deceased, lived to the ripe age of 23 y/o eating only the original Whiska's recipe dry chunkies. Our "new " cat was fed only the Whiska's old recipe and with the new change, has simply gone off his food completely .He has lost condition and his coat has lost the lustre it had. He is very lethargic and has lost his high energy levels. There is definately a problem with this product. We have tried all the available flavours with the same result. Cats just don't like it. We have spoken to several cat owners who all complain of the same symptoms which is of concern to all and needs to be addressed or clients will simply stop buying this product.