Only the IDP is an official document, I'm afraid. The Int. D. Licence is a completely unofficial document and if you look on their website it tells you it has no status.
Certainly in UK the permit is very easy to get and is cheap. Sorry!
The permit is a fancy grey document made of paper that lists the rules and validity based on some international convention and is in several langauges.
The booklet that I applied and paid for is based on the Vienna Agreement. The rules and regulations are quoted in several languages including Korean. The word ‘permit’ instead of ‘license’ has been used in the English section of the booklet.
The cover of the booklet is as follows:
International Driving License
Permis De Conduire International
By the way, the validity is one year only.
Where did you get it from? There are, I'm afraid, lots of bogus firms selling unusable documents but you may just have one that was correctly issued with a wrong name.
I got it from the Main Post Office in Dubai which is one of the autourised places. For my application, I had to submit my local driving license and UAE ID. Of course, there is a fee for it.
I used a similar driving license in Japan too.
in that case, how long have you had your license? I have heard other posters here say that most agencies will not rent if it is valid for less than one year.
28 years of driving experience
That all sounds as though you have the right document. Which car rental firm refused you?