This Part shall not entitle any person to salvage remuneration—
(a) in respect of salvage services rendered contrary to any express and reasonable prohibition of such services on the part of the vessel or aircraft or by the owner of property to which such services are rendered;
(b) in respect of services rendered by a tug to, or in respect of the vessel or aircraft or the cargo thereof which the tug is towing, except where such services are of an exceptional character such as are outside the scope of the contract of towage;
(c) if the person has caused the distress giving rise to the salvage, either intentionally or through negligence;
(d) if and to such extent as it appears that the person concealed or unlawfully disposed of any property salvaged.