Nothing in this chapter shall be taken to give the Youth Authority Board or the director control over existing facilities, institutions or agencies; or to require them to serve the board or the director inconsistently with their functions, or with the authority of their officers, or with the laws and regulations governing their activities; or to give the board or the director power to make use of any private institution or agency without its consent; or to pay a private institution or agency for services which a public institution or agency is willing and able to perform.