Someone, please help! I am an amateur at vegetable gardening and would really, really appreciate some guidance ASAP. Thanks so much.

What a clever idea, having a product made in the same country where most people will buy it, whoever heard of such a thing!?! Let's hope, with rising fuel prices, it's the beginning of a trend.

I'm not a pro, but I've been doing a lot of research about this exact issue in the last month, in preparation for a DIY project. (I was a professional woodworker before retiring, just not a flooring person). I just want to reiterate one thing about Luaun and to suggest what I think is the reason for the failure. First, luaun is plywood, and, yes, it is commonly used, but it's a poor choice. It's smooth, but has many voids, which can compress after the vinyl is installed, with results similar to what you already have. Do not let them use luaun. The birch plywood mentioned above is good. Multiply is one brand name that is carried by my local Home Depot. It's 5mm thick. As for what happened, I don't think what you are seeing is the underlayment having moved or buckled. Rather, I think they simply layed the vinyl over an uneven underlayment. Sometimes it can take a while for the vinyl to "sink" into the gaps, so you start out with a floor that looks fine. But as the months go by, things begin to get uglier. The only reason I point this out is to suggest that you be skeptical of any claims they might make about your house settling or "unknowns" or whatever. Now, if you had walls built below this floor or something in the meantime...and they pounded them in, it's possible this could lift a few joists, causing something like this, but, setting that aside, your 30 year old house probably did most of it's major settling a few years back. Essentially, I mean to say that they did it wrong, period. There aren't any "unknowns" here that they can summon up to garner your sympathy. As for the appropriateness of installing Multi-ply (not luaun) directly over your existing vinyl, I'm not qualified to judge. My suggestion would be to call another flooring expert in to have a look. Tell him/her in advance the reason for the visit and offer to pay for an hour of time. The frustrating part about this stuff is that, even if the folks who installed this are willing to work with you, they may not be qualified to fix their own work. I wish you well.

A fix, won’t. The problem is the crack, inherently peters out toward the sink bowl, with the widest portion on the edge. You may be able to flow enough repairing material into a portion of the crack, but you end up with an area of the crack that is too narrow for the repair material to penetrate and bond. What happens then is the crack below the bonded area slowly spreads and reappears, like a bad penny. If you know the actual material, have the correct tools and materials, it might be possible to open the crack enough through its entire extent to repair it correctly, but it’s a far from simple or easy task. Also, on some materials, the work to prepare for the repair sometimes renders the unit unrepairable...much like a bullseye on a windshield can suddenly become a huge crack when they attempt a resin repair.