I tried to contact them when I wanted to buy my Tongxin motor last year. I couldn't get through at the time, but have had some communication since.
It is true that Tony Castles is hard to get hold of but I think there are some other issues too, connected with (first) reliability of Tongxin controllers and (now) availability of supply.
I had a message from Tony (a PM on this site) a few months ago saying that controllers were now more reliable (and the Cytronex experience supports this). The AtoB site now says in its review that there are supply problems - perhaps not surprising given the big corporate deals Tongxin has pulled off.
As Flecc says, I'd look elsewhere for a Tongxin (Tony's 'Nano' kit is just a Tongxin - as far as i know there's nothing else added to it, apart from a battery). There are other potential suppliers - firstly John on this site who is expecting them soon. Also, if he runs out, I think the Austrian supplier, specialbikes.at, has had them in the past and may do now.