Hey bro, do understand your feeling. If i've encounter the same of unprofessional SA, wil get mad as well. 
I'm CT buyer, booked it after i've visited the VINA showroom (Wont comments any pros & cons of both prop here). Coincidently the Vina SA (guy) can't provide info in professional way when visit the Sales gallery too. But I was in rush too so cant blame anything.

Luckily I didnt encounter the same scenario as you above as most of the buyers met the SA personally One to One to understand further details of the projects. So we have decent time to know more about the prop and SA explained to me very patiently and friendly. I remember I've took 2hours to discuss on it with SA while lunch.

VINA is a good project too. But if you r keen on CT, do give SA a call for meet up.
Heard launching in September.  2 new scale models wil be comin early Aug as mentioned by Chulk,

which agency are you from? Metrohomes?