We got a potting shed from them last year. We were very wary from the Google reviews, and also from visiting their "showroom", which was an odd experience. However, we couldn't find exactly what we wanted elsewhere.
Because of the reviews, we spent ages checking the delivery before signing it off. We found a broken part, which we sent back with the delivery drivers, and wrote this clearly on their form, as well as taking photos. Dunster sent us a replacement part, although it was a bit of a faff.
Also, we had been advised that it would come with flooring. It didn't. We contacted Dunster, and they sent us some flooring after all, as their salesperson had advised us wrongly, and we had that in writing.
Therefore, although I was expecting the worst, and communications weren't great, I would use them again. And the potting shed is actually lovely!