I got Alex to come to my place the other day too. Vincent was there as well. Finally confirmed with him after spending quite a bit of time (8.20pm to 10.30pm) to choose the windows, grills, colour, etc. Me and the Mrs were very happy with the service we got from Alex and Vincent. In fact we were so sold on his service we decided to change the service balcony door and window too with him. Like what a fellow forumer mentioned, he told me no need for payment now. Only need to pay once the windows are up, and complete the rest of the payment once the grills are up.
Vincent is going to get the house keys from me tomorrow so that they can remove the grills first before my ID starts the hacking next Monday. Will try to post some pics once they get the window frame up.