When you assemble a bicycle, please insert the seat post into seat clamp (under the saddle) and tighten before you insert the seat post into the frame, then the seat post will not drop into the frame. If you insert the seat post into the frame (without saddle assembled), the the seat post might drop into the frame and get stuck by accident, it is quite common, and we're sorry for this. Don’t worry, let's try: Turn the bike over. Make sure that the bike is protected from being damaged. Especially the grips and saddle. Put a towel over the bottom bracket and the seat tube. Using a rubber mallet, strike the bottom bracket and seat tube lightly, make sure that the painting will not be damaged. Be patient, the seat post will not come out at once, it will take a while. Keep trying, the seat post will eventually come out. If you take the bike to a bike shop, they will do the same, they will keep going until the seat post slides out. Also, please give us a call. We'll see if there's anything we can do.