Lets talk about what is legal what's not.
Seems like you guys can't really understand what can you do or you just playing the fool who doesn't understand why you get banned.
"He came to me to being killed"
"I didn't know killing AFK players is not okay"
etc.
There is no definition of killing AFK players since everyone get spawnprotection when they die, and it lasts until they press a key. So killing someone who might look like afking its a lie, they deliberately press a key to be able to get killed then stop moving.
These accounts have like 1000+ more deaths and only like 10-20 kills, nobody is that bad to achieve a stat like this when they play normally.
You should know what stating means. Fighting with each other is okay. That is how you should play on the server. But by fighting you can't achieve 100-200-300+ more kills than deaths. If you fight with someone then you will have deaths as well, even if you are better. With headshot enabled, it is impossible to get 3-4 times more kills than deaths.
I'm so good that i can get 5 kills without dying. Yes sure. 
I always go to jail with 6 kills and waits, so thats why. Yes sure 
If you are that good, then record yourself and post it!
I will unban you if you provide a proper proof that you both were fighting with each other, but you were just too good. Post the whole fight scene, not only 1-2 minutes. Everyone can make fake scripted videos where they fight, then they lie about the rest of the kills.
On killing low levels:
What is low level? Someone whose level is like under -15 than yours until level 60. Between 60-100 you both have all the significant weapons, and both of you have efficient ammount of hp.
Nobody belives that a low level account deliberately goes to your place and asks for being killed. Its like the opposite term: You (as high level) go to the low level's place to kill it.
Of course there are situations where the low level guy is pesky and fights with you, annoys you, but when fighting you won't get kills within seconds without he kills you. With headshot enabled a low level player can also kill a level100 player.
If someone INTENTIONALLY goes to you and he is a low level player and wants to fight with you, then kill him. It will be only a few times. Don't say that you got kills by this way more than 10 times ... Nobody will drive from LS to SF/LV for being killed. Yes it can happen like 3-4 times but then he will learn that it makes no sense. Record yourself and prove that I'm wrong. You can record every fight scene then upload them one by one, or in one video. You can even help me by writing /thetime or /time or /servertime in the chatbox so I can see better when the fights happened.
What if you both do fighting? Don't go to LS and search him. If you really want to fight with him then connect with a lower level account which meets the requirements (no higher than +15 levels). Why? Because hp and available weapons matter. If you don't have such an account then just go away from the guy, don't fight with him. Or Record yourself to prove it was a real fight 
In any case you can record your own gameplay with OBS then upload it to youtube.com and link to the forum if you feel you got banned for a mistake. In the video we should see that both of you fighting. You can upload the whole fight scene (10-20-30 minutes). Not just 1-2 minutes where you fight, and in the rest 28 minutes you stating 