Re your Post
I always found getting Overflights via AFTN with very few exceptions is virtually Impossible,
Lots of these countries are not concerned within reason who Overflies ,
What they are concerned about is WHO IS GOING TO Pay
They have had so many people overflying and then not paying there bills I am of the opinion they will only give the permit to an ac credited agent who has lodged funds with them,That way the take the overflight fees from the funds and the agent tops up the funds before they expire.
Dont try to cut corners trying to save 5 Bob on your Overflight and then you are told you have to land in the Country you are overflying,That will cost you a lot more than 5 Bob.
If you want to overfly you have to get an agent to get the permit on your behalf or run in Glue via AFTN get an Agent every time
Please be assured I arranged Many Overflight clearances with an Agent every time never had any problems in 30 + Years
Best of Luck
Gerry X Northern Executive Aviation