How long have you had the chilli plant?
I have the same problem, although sometimes the plant can manage to
survive well along a not-so-sunny corridor, provided you prop it up
higher with a pot stand or something, so that the plant gets more
light. Also, regular doses of fertilisers help to make the plant
healthy and more resistent to disease.
However, the cloudy weather lately plus the haze isn't helping, as
the haze tends to block out much light. 