I would have thought that Babis in Kalyves, opposite the EKO filling station, would have one. Failing that, there's the car accessory shop in Haniá which is past Lidl and turn right. You go up that (Mournies) road from the National Road, past Lidl and on until you reach a set of traffic lights where you can see a Bridgstone tyre depot across the road and to your right. (It might be an extension of Gogoni street but I'm not certain.) Anyway, you turn right past that tyre depot and carry on about 100m. The car accessory shop is on the left and the road is quite wide so you can usually park on the right.
In case you need it, the word for charger in Greek is "forteestees". (Thelo ena forteestee avtokeeneetoo - dhodheka volt.)