I would try Kafkas
. Go into Chania on the Omalos road and turn left onto the Kissamos Old Road at the 5 way junction. They are on the right at the top of the hill just before a Silk petrol station. If you get as far as AB you have gone past them. It looks like a lighting shop, which it is, but they also sell all sorts of products for electrical installations. A lot of electricians use them.
There is another big lighting shop on the right going into Chania on the Omalos road about half way between the National Highway and the Kissamos Old Road junction. They also sell a lot of products for electrical installations, again to electricians.