Are they green or red chillie types?

Your chilli 's will ripen, it does take a while, my peppers are still green too.
They love the heat, the hotter the better for hot chillis, so keep feeding and watering, during this month and the next and you'll see them begin to change colour as they ripen.....
in a good year I can be picking peppers into october, with a small chilli plant if the weather turns cold you could bring it indoors to a sunny windowsil

You can also pick them when they are green, taste one first. They probably won't be as sweet as fully ripe red ones though.

chillies when green aslo can pack a bit of a punch so taste with care!