advice on a conservatory roof?

I would appreciate your advice before I tackle the builder who has installed a new triple carb roof on my conservatory.

The original roof, some 7m wide and 4m deep, was laid on wood rafters. The polycarb (triple glassed) sheets had a series of aluminium capping bars holding them down onto the rafters. The bars were screwed down into the rafters between each pair of sheets. The width of the new poly carb sheets is metric and hence different from that of the original roof (1985). The builder laid the new sheets on the rafters without cutting them to fit; as a result, the joins do not coincide with the rafters. The sheets are joined where needed, using a lightweight aluminium strip under the joins, with a simple "plug-in" plastic seal over the top, (which seems to be waterproof). This arrangement obviously means that the weight of the roof is taken by the rafters. However, because the sheets cannot be screwed down to the rafters, each one is held in place by two screws at the top and two at the bottom through plastic cups (approximately 4cm in diameter) with rubber seals etc .

Because the sheets are some 4m in length and are only secured at the top and bottom, the whole roof lifts and flexes if the doors are opened and the wind is blowing!! Not very satisfactory.

How should the sheets have been secured and what needs to be done to solve the problem? An expert's view would be very welcome.

Regards,

Peter Lacy