How many tambon are there in Thailand?

I always thought that the question on the number of Tambon (subdistrict) is a trivial one, as several government publication list the number of subdivisions, and they all consistently give a number of 7255 (or 7424 if including the subdistricts of Bangkok, which however actually are a different type of administrative unit) - for example the 2012 list from DOPA, or the 2013 list I didn't noticed yet. I never questioned that number, as I thought the department within the Ministry of Interior would know their numbers well.

But now I am in email contact with someone who has compiled his own lists of municipalities and subdistricts, and then cross-checked then with my spreadsheet. Quite helpful, it showed several cases where I had small mistakes within my lists, as well as clearing up some in his lists. He had a few more subdistricts in his list than me, and I also had a subdistrict named Som Kai (ตำบลสมก๋าย) in Chiang Mai listed as an active subdistrict, even though it was one which was not created, but got a the geocode 50061400 assigned already. But after removing that one, I noticed I still have one subdistrict too much - the corresponding sheet had 7425 subdistricts, thus 7256 Tambon.

Checking with the population numbers from DOPA, the additional Tambon stayed, apparently there are 7256 populated Tambon. Next step then was to check with a Excel sheet showing the subdivision numbers for each province, which also had 7255 Tambon altogether - and with that one I could nail it down to be Nakhon Si Thammarat province to have the additional subdistrict. According to that spreadsheet (and several other sources), the province has 169 Tambon - actually a lot of source show a number of 165, even the website of the province administration itself, which is even more wrong. But I have 170 Tambon, and with a 2003 book listing all the Muban I was able to find the culprit - Pak Phanang district is listed there without the subdistrict Pak Phanang (ตำบลปากพนัง). The only thing special about that subdistrict is the fact that it is completely covered by the town Pak Phanang (เทศบาลเมืองปากพนัง), and thus has no subdivision in to Muban anymore, nor any village or subdistrict headmen. But that is not unique to this Tambon, there are several of this kind in larger towns or cities. In fact, the subdistrict was identical with the area of the town until the town was enlarged in 1993 [Gazette].

Center of Pak Phanang district in 2003

With two offices within DOPA contradicting already, I wasn't able to find any more solid proof in either direction. amphoe.com for example includes a map showing the Tambon of Pak Phanang with only 17 Tambon, even the Royal Gazette is no help - obviously there is no announcement abolishing this subdistrict, but an announcement from 2003 defining the boundaries of the subdistricts again only lists 17 subdistrict. Another announcement from the same year however on land expropriation includes a map which shows this subdistrict.

If anyone can help to clear up this confusion I would be happy, so far I can only find that something is very odd around there.