Draughty Patio Doors

[Tristar]

My apologies, I posted this first in Building in error.
I have recently had new Halo sliding patio doors fitted. There is a draught under the fixed portion of the door, which the company claim is inevitable due to drain holes in the frame. There is also a draught from the joint between the two centre vertical frame edges where the doors overlap.
Given that the fixed and sliding centre vertical frame sections are the same width, should they be aligned and vertically parallel, such that when closed I can only see the inner section? With mine I can see about 10mm of the fixed frame because the sliding portion appears to not close enough, suggesting that they have been made slightly too large. It seems as if the vertical brush seals are fairly wide apart. The company claim this overlap is correct and is how they are designed.
They have been today to try to fix it, but there is still a draught from both places.
What are the regulations, if any, regarding draughts and fitting standards for such doors?
My 30 year old tilt and slide previous doors sealed perfectly and draught free until the rubber started to deteriorate recently, and I only fitted new as I assumed that standards would be higher now.

 

[Tristar]

Thanks very much, that is what I expected. The company has been to fix it, claiming that the overlap of the doors is correct, although I said I did not believe it. They have removed doors and refitted, now with minimal overlap, however there is still a draught from both places. I am now told that they will ask the manufacturers to examine them, however, I cannot believe that any improvement can be made. So disappointing after my excellent previous doors.

 

[Tristar]

Further on the post. The temperature yesterday outside was -7C, and when I measured the air temp with a handy gizmo I bought a year or so ago, with the room temp at +19C, the temp adjacent to the bottom of the fixed frame was 0C! And the air midway up next to the join with the slider was +11C. I have told the supplying company I am not accepting it, so he has said he will arrange a visit from the manufacturer. I cannot see how they can improve this, as the fitting appeared to be conscientiously done on the refitting, although there is still 3 or 4mm overlap at the centre.

 

[Tristar]

Update on this. The supplying company has referred the problem back to the manufacturer, who has stated that the doors are perfectly satisfactory, and that the cold air along the bottom of the fixed panel is due to outside air accessing the voids in the bottom of the frame via the drain holes in the frame.
This may well be the case, but the fact remains that cold air is finding its way into the area , presumably through the brush seals and not via the frame itself, as the frame temp in this area is 5 or 6 degrees higher than the air temp next to it.
My 25 year old doors had no such problems with cold air leaking in.
I do feel sorry for the supplier, who appears to have fitted the doors OK, but is, perhaps unsurprisingly, getting nowhere with the manufacturer.
Does anyone know of any reputable independent double glazing surveyors who offer consultations on such issues?