I'm sorry you had such a bad experience trying to get a new kilt.
I've had varying experiences in that particular store.
When I was looking for ghillies for my sister's wedding the staff knew exactly what they were talking about and helped me to find a shop that had some in my size. (They even went to the trouble of phoning them for me to have them kept aside.)

On other occasions I have had then simply ignore me from the moment I entered to the moment I left.

Phil: I'm not sure of any Kiltmakers in Renfrew street at the moment but I'll certainly be looking out for them when I am next in town.