I need some help.
I have made my desing, adjusted the sizes on metric and scale. I sent it to chapeways for 3d printing and it worked beautifully, but when I sent it to some 3d printting services on my area, the sizes got over 39 times smaller. Does anyone know how to solve this problem?
Check the units in the blender Scene settings or talk to the printing service or open the stl in some other application to check its dimensions
1 cm = approx 0.39 inches. Seems a big coincidence given the number you mention in your post.
Which other program should I use?
You asked your question in the wrong section.
Stl-Export has scale option, use that.