I wash my show TS's in the washing machine and hang them to dry. You might try getting them wet and then stretching the knee patches back to their original shape when they are wet. My breeches have been washed numerous times and are still in great shape. Good luck.
Take it back to the dry cleaner and see if they'll pay to fix your $200some pants.
If they won't, you can try maybe dampening the patch and working in some leather therapy conditioner or just send them back to TS for a replacement patch. I'm sure they'll charge you, but I don't know how much.
I bought a pair on eBay once that looked like exactly the same thing had happened. I took them to a tailor and had them take the knee patches off to release the fabric bunched underneath. Then they just sewed the patches back on. Worked like a charm and didn't cost much at all if I recall correctly.
I'd also tell the dry cleaner they owed me a new pair though!