Fieldstone Windows & Doors Ltd

We used the Fieldstone becuase they came highly recommended by my friend who changed all of her windows/doors using this company.
The owner, Ken, is very knowledgeable and friendly. He made sure my order was exactly as per the architect's drawings. Suzie, the marketing director is amazing. It's pretty much due to her outstanding interpersonal and professional skills that I decided to use Stonefield. I worked with the builder, who could have gotten different windows for me but I chose to use Stonefield due to the above mentioned reasons. Plus their price was fair.

The windows/doors were delivered pretty much on time with only a very small delay. The majority of doors/windows were in a good working order. No issues.
The sliding door supplied by the Stonefield has turned out to have a design fault. Stonefield promised to contact the manufacturer to resolve the issue. That has not happened to date. It's been approximately 6 months since I communicated my concern to them. I have sent numerous follow up emails but no answer cam back.
Also, one window has a manufacturer's defect. I have been repeatedly asking Stonefield if they would get me a credit from the manufacturer but it has not happened either.
In fairness they came to fix a couple of mismatched handle covers fairly promptly.
The Customer Service rep - Tancy - lacks basic communication skills and the product knowledge. She either asks the questions that she already asked before or simply doesn't respond to emails. To quote my husband's: Who is she related to?
The situation makes me sad for a few reasons:
I considered using this company for another project I had in mind for both supply and installation.
I really feel that the owner went out of his way to make my project a success but the incompetence of staff responsible for the follow up has really brought the overall impression down.

I am still hoping they will resolve things for me.