How to Remove a Stuck SIM in the tray.
If you inserted a big SIM in the tray and without removing the cover.

I have faced the same problem and I managed to get the sim out without removing the back.
Simply heat up a pin or a needle.
Use pliers to hold it and carefully stick it to the edge of the sim.
Dont forget to remove any plastick cover around the phone to avoid accident touch as it will melt.
Heat up the pin till it is red .