Hi Rocker, If what you say is true then report the builder right away...If in later years there is an insurance claim, YOU will be held liable as per building regs as being the nominated installer ie the electrical installer. He has removed highly spec fittings and replaced with low grade alternatives which was not on the agreed rewire.
2.1.2.1 Electrical
BS 7671 requires in Regulation 131.8 that no addition or alteration, temporary or permanent, shall be made to an existing installation, unless it has been ascertained that the rating and the condition of any existing equipment, including that of the supplier, which will have to carry any additional load is adequate for the altered circumstances and the earthing and bonding arrangements are also adequate.
When carrying out an addition or alteration to an existing electrical installation, the installer must confirm that the old installation meets the current requirements of the Building Regulations in so far as it affects the new installation and is adequate in all respects to supply the additional load if any; such that the new work is safe i.e. complies with Part 1 of BS 7671: Requirements for Electrical Installations.
In particular, the rating and the condition of the existing equipment belonging to both the customer and the electricity distributor can:
u carry the additional load, u provide adequate shock protection (fault loop impedances must be appropriate for the
protective devices), and u the earthing and equipotential bonding arrangements are satisfactory.
Defects in the existing installation affecting the alteration or addition must be made good. Defects in the electrical installation identified during the work and not affecting the addition or alteration must be identified in writing to the person ordering the work.
and
Additions or extensions to a building must comply with the Building Regulations. If wiring is carried out in an extension to an existing building, the wiring to the extension must comply not only with Part P but also with all the other appropriate requirements of the Building Regulations. There is no particular requirement to ensure compliance with the Building Regulations with respect to other parts of the building not affected by the extension, alteration or addition. The compliance with the Building Regulations of the existing building must not be degraded. For example energy efficient luminaires must not be replaced by less efficient luminaires however insistent the customer may be. Walls and ceilings must not be degraded by chases, drillings, etc.