After you change the quantity please click the "Update" button!
Please note: fractional numbers should be entered using dot as decimal separator (e.g. if 2,5 is the desired quantity, it should be entered as 2.5 for kilos and meters, and under the product name you can find the unit of measure).
If the last selected product+option(s) is not in the basket or the quantity is less than what you have entered, then there is no stock of the product or only the quantity shown here is in stock!