Jordy...it probably because "Fibre to the Cabinet" hasn't made it to your Telephone Exchange Area yet.
Look out for new green cabinets mounted on the pavements, sited close to the old, existing ones. These new ones are a little bigger, have small louvers in the casing and a yellow Laser sticker on the side. But register with BT and you will be in line to get Infinity as soon as its up and running.
I can explain "Fibre to the Cabinet" more fully if you require ( I am Ex-BT ! )