I think it all depends on who is on to respond, or something like that.
I've gotten responses within 2-3 hours of submitting them, but then again I still have some open with no response from like a month ago.
It depends on what the ticket is on. I've had tickets be answered within a few hours (usually simple glitches that get a "thank you for bringing this to our attention" reply), and some have been open for almost a year. I've seen people have tickets open for over 13 months before they get their accounts back.
When TnT sees a ticket that's a potential pain in the ass this is what goes down:
"Oh look a new ticket. Wait, this one looks like a bitch, I'll just let someone else deal with it."
*2 years later*
"What the fuck, this is still open? Whatever, it's not like it matters anyways, let's just flip a coin and call it a done deal."
"Oh heads. I guess the lucky kid gets the account back. Anyways, where the fuck did you put my beer? It still had at least half left!"
I had one for a unfair frozen account, yet have to get a reply and its been about what, six months?
I also sent a ticket about a perma a few weeks ago.
Both are still open.
I also had a ticket about a NC item someone accepted. They told they had sent me the item but I got nothing. TNTs only reply (because I wanted to know if the other user had indeed sent) was that he received his part. Never got my item back. -_-