Hi and welcome to YT. I can relate to the shock. The first time Hot Rod went to the groomer, he had lots of black and a white spot on his head. Well, when he came home most of the black was gone and he was so different looking that I wasn't sure it was the same dog. The 2nd time every last bit of black on his head was gone..
He looked as though we took the head ox a totally different dog and put it on his body. His entire head was white and body was black. All his puppiness was gone, I was near tears.
He eventually started to turn a creamy color which turned gold. It was a process but I was so sorry to see his black tips gone.