APO Product Options, Variants

This app used to be GREAT - absolutely perfect for what we needed. Why can't these developers leave well enough alone??? They are constantly tweaking and changing. They want me to upgrade, and if I do that the app will no longer meet my needs at all. We need to be able to tack a stock product (think a large blue T-shirt) out of stock, apply a customization (iron-on) at an additional charge, and append the sku to reflect the customization. Used to work beautifully, now has issues, and that facility will be removed completely if I upgrade. The old version has been changed that causes some issues, but at least it is still tracking inventory and linking by product ID, which is critical for my business. If they keep this in the new version they would have a 5-star app.