We had our DIY Kitchens kitchen installed in June. It's lovely, and excellent quality.
We didn't get quotes from Wren, but from an independent company, Wickes (which is flat packed, and therefore takes longer to fit, as they have to build them before fitting) and Howdens (x2 quotes). They were all between £26,000 and £33,000, including fitting and worktops, but not including appliances.
DIY Kitchens was £16,000 for the kitchen units and that included eight AEG appliances. Then we paid £3,500 for quartz worktops and paid an independent fitter £2,500 to install it. For our own peace of mind, we also got an independent kitchen designer to check over our plans as we had building work done and were aware that with kitchens, millimeters matter. I think we paid him about £350. DIY-Kitchens are ready-assembled, apart from our corner walk-in larder, which would never had got through the door if it had been pre-built!
We had 86 items on our delivery. Two items were not sent on the delivery as they hadn't passed quality control, but other than that (and they were delivered very quickly) we had no issues with our kitchen. There are numerous groups sharing horrendous tales of their experiences with Wren.
Watch this video by Nick Morris. He compares on a like for like basis, kitchens from Wren, Wickes, Howdens, Magnet and DIY-Kitchens. It was his video that made me go with DIY. There is a Facebook group - DIY Kitchens - Design and Planning Forum and Finished Kitchen Reviews- UK - where people share inspiration, ideas and will critique your designs.