Frustration and amateur photographers are directly proportional to each other. Frustration is the thing that makes somebody a better or a bad photographer. The time when a photographer is frustrated and there can be a million reasons which i am going to mention later, this is the time when a photographer decides to either work harder and try and be the best or just throw the camera away.
I have been through this time and i loved it, i am thankful to God that i did not lose hope and i decided to work harder and here i am doing a much better job than i used to. The one major reason of that frustration is when you see a photograph and you love it and you want to capture a photo like that, post process it so it looks either better or almost the same as the one you saw and you cannot get it right. That is where you feel frustrated, trying again and again and not getting it right. That is the moment when you have to decide that you have to do it even if it take your whole life to learn that, you have to have that sportsman spirit inside you.
There are many other photographers whose work you like and you want to create images like that but you cannot and you need their help and they won't most of the times so there is no need to be angry, they are not your servants its their wish if they want to teach you or not, and thats because they feel INSECURE that you might become better than them so Go on prove it try harder and try to be better than them. That is what i did, i was not taught so i decided that one day i am going to be better than you and Yes i can proudly say that i am better than them today.
This is my advice to you all out there we are all amateurs and we need to learn a lot so do not lose hope because of one small thing that you cannot learn, its only for sometime that you cannot get it right but if you try harder you will definitely do it, Trust me.
Pick up those cameras go out and start taking photos and keep practicing and enjoy!