Suddenly a LOT of play in the steering wheel

Have owned a 2004 Lexus IS 300 for 9 years! 75,000 miles now. I have been diligent about taking the car in for servicing on a regular basis. Just had my 75,000 mile service during which they rotated my tires (both front to back and vice versa). When I got the car back, there was a lot of play in the steering wheel (I was almost fishtailing down the freeway on the way home). I immediately drove it back to the dealership and complained. They said that the only thing that they did that could possibly affect the steering was the tire rotation. So they rotated them back and the steering went back to normal. But they warned me that the tires with the most tread were now on the front and for safety reasons, they should be on the back.

I had made a reservation to get my wheels resurfaced the next week. They talked me into purchasing two new tires to replace the ones that were on the back. After they replaced the two tired and did the resurfacing, the same situation presented itself. I took the car back to the NTB location where I had purchased the last set of tires. I had purchased the lifetime front alignment package, so they suggested an alignment.

after the alignment, the problem was a LOT better, but not completely gone. Over the last week and a half it has been becoming worse and is now worse than it was when I picked the car up. The dealership claims that they have no idea what is going on (although I suspect that my surface advisor doesn't have much depth of experience). They have offered to try to repair the issue, but I am nervous about giving it to them when they don't seem to have a clue what is going on.

Any suggestions?