Double Glazing quote

blindman

Measurements-My rough brick to brick

Windows 17 in total (5 Non opening.)

120cm x 100 x 10 (3 not open)

90cm x 100 x 2

60cm x 100cm x 2 (1 Not open)

66cm x 66cm x 3 (1 Not open)

Doors
210cm x 100cm x 3

Patio
210cm x 100cm x 1


Got 3 quotes from Independents who all seem to use Liniar

All A rating glass and secure doors (?)

Cambridgeshire area.

Quotes range from

£7k

£10K

£13K

The £13k is for a Oak effect and doors at £1k each (his words) and the others just plain white (no detail on doors) so I would assume that would bring it down to around £10K

All are local and have good reviews on various sites.

So my question is:-

Why is the cheapest £3K less or is this a fair quote?

What do I need to ask this firm to determine why their quote is way cheaper?

Thanks