(1) It is not permissible to agree on or to bill for lower fees and disbursements than those provided for in the Federal Scale of Lawyers' Fees (Bundesgebührenordnung für Rechtsanwälte) in as far as nothing to the contrary is set out therein. In the individual case a Rechtsanwalt may give consideration to a client's particular personal circumstances, particularly the client's impecuniousness, by lowering his/her fees or by waiving fees or disbursements after bringing the case to a conclusion.