Review on Modway Attainment Drafting Chair Black by Isaac Logan

I bought this model on purpose because I needed a size of at least 31 inches. When I assembled it, it was only as high as it took to reach its full height, but almost as soon as I actually climbed in, it started to sink. I tried to return it but I couldn't recognize the item. The air shaft simply slides into the bottom of the post, but once in, you can never pull it out. I persevered, hoping it wouldn't sink any further. Now it's too late to bring it back and the altitude keeps dropping. Now it's fully extended to 28 inches, which is well below the height I need and I seem to be sticking with it.