Does anyone know a cure for reeds that are warped at the tip ?

Wet the reed. Place the thin part on the mouthpiece. Press the thin part of the reed with your finger(s) and move the thick part of the reed back in forth.

Do the plastic cases help they seem to be quite a tite fit. I thought they would keep the reeds flat while not in use am I wrong on this?

Agree with both posts. Make sure reed is wet when putting it on the mouthpiece facing. Tick it gently with finger, holding thin part down with thumb. To prevent warps in the first place, keep reed moist. Either by keeping it on the mp (rinsed clean of course) using a mp cap that has no holes in the top (use tape to cover holes if needed). Or, keep reed(s) in the plastic reed holder (metal not so good). Make sure you keep reed damp--not soaked)-. This usually means re-wetting it every 5 hours or so (before you go to bed, etc.). Some will argue this shortens the reed's life and are probably correct. But you know that you will have a non-warped reed that you can depend on to play well (MOST of the time).

I would think reeds were pretty delicate. I haven't heard of the term warped before, but after reading about it I would just buy a new reed. The only cure I could think of is prevention. Most quality reeds you can buy have their own reed case to protect them. If the weather is hot most of the time I wouldn't keep the clarinet outside its case when not in use. If the reed breaks too often, buy stronger reeds. Then again you'd have to be playing a lot to go to extremes.