Hi there, I received this letter today..I believe its for alleged unpaid charges for an alleged contravention at Gatwick airport. If this was received then I would have appealed right away, I did not receive the initial letter.
On the back page it says that this cannot be appealed, so I wondering how I can get this back to the original NTK and then file my appeal accordingly.
Thanks as always

I wondering how I can get this back to the original NTK and then file my appeal accordingly.
You probably can't - NCP won't be interested in any conversation that doesn't involve you paying. That's not to say you should, of course.
The drop off setup at Gatwick is known to be shoddy - have a search for 'Nosy Parker' on PePiPoo, he has posted at length on Gatwick threads about the issues there. He has recently joined this forum, so with any luck may chip in on this thread in due course. Here's one example of a case he was helping with that went to court, and was successfully defended:
http://forums.pepipoo.com/index.php?showtopic=150483.
Have a read of a few of the threads, and then pull together a letter that outlines all the reasons why no money is owed (feel free to share a draft here for feedback). Whilst they won't accept any appeals, and will take great joy in reminding you of this, it is nevertheless sensible to set out your stall - if nothing else it shows you are reasonable, and hopefully shows that you're up for a fight.