Things to Check Before Buying Modular Furniture

Ask what the carcass is made of. This is the board you never see and the part that fails first. Moisture-resistant ply or HDHMR in wet areas; ordinary MDF is not acceptable under a sink.
Ask about edge banding. Unbanded or thinly banded edges swell the moment they meet water. 2mm banding on exposed edges is worth asking for by name.
Ask which hardware brand, and what warranty is written on the quotation. Hinges and channels are what you operate every day.
Ask whether it is manufactured or bought in. A unit that makes its own furniture can change a size or a layout mid-way and has to answer for the quality itself.
Ask to see the finish sample in daylight, not under showroom lighting.
Ask what the quotation excludes — counter material, electrical, chimney, transport and installation are the usual omissions that appear later.
Ask how the site is measured, and whether you approve a drawing before cutting.
Ask about the delivery and installation timeline in writing.
And ask what happens after installation: who comes back to adjust a shutter that has settled, and for how long.