I was incredibly lucky that our initially booked installer was non-communicative so I had to look for an alternative. Found national appliance parts and the guys on the phone were absolutely awesome. No bs, no non-sense, they told me exactly what I would need, how much it would cost and how long it would take.
Then they sent an installer named Joseph ... omg, what an awesome guy. Super nice, super polite, once again, knew exactly what stumbling blocks there would be, told us EXACTLY how to deal with them and what to say to our builder to get them fixed. He went above and beyond at every turn. We had some high end appliances that we were concerned about but he was certified in all of them and was incredibly knowledgeable.
I so wish that I had also just bought my appliances from them. These have me as a customer for life now. I'm not doing anything appliance (or even just electrical and/or plumbing related) without talking to them first.