In most orders the price stays exactly as you saw it when booking. It can change for three reasons, and you hear about each of them before work starts, not at payment.
The most common case. If it is one or two uncounted sashes we do not even raise it and the price stands. For a bigger difference we tell you — a window costs 199 CZK. Watch out for box windows, common in the older buildings of Pilsen city centre and Jižní Předměstí: they have two rows of sashes behind one another, so the work is roughly double.
A standard cleaning was ordered, but the flat is full of construction dust. That is removed differently — dry and in several passes — and it carries a rate of 39 CZK per square metre with a minimum order of 1,000 CZK. If it was only a cosmetic repair without sanding, the rate does not apply.
When the scope is clearly larger than ordered, we say how many hours are needed and offer extra hours at 319 CZK each. We usually see it right at the start. If the misjudgement is ours, you do not pay for it.