Hi WW - back in UK tonight - but - if you walk from the Otogar towards the main road lights - you cross over the road at the garage and the shop is opposite the garage on the other side of the road.
When I went in there last year there was a very nice Turkish chap in there who could speak English and he said basically "this place has been going a few years and the service is very good and the quality is good - I am replacing all the windows and doors in my house 11 in total" - I then got a quote which was better than a few I had got on the sanaiye and the quality did look good - so that will be my first port of call :-)
