How to get to Bangkok Immigration at Cheang Wattana by bus?

I'd like to bus to Immigration from either Mo Chit or Victory Monument stations.  Seems the options are bus #52 from Mo Chit or bus #166 from Victory Monument.

I've taken Bus #52 from Mo Chit BTS before.  I've read about 14 thousand times that Bus #52 turns left at IT Square onto Chaeng Wattana, and you can get out in front of the Government Complex or CAT Telecom.  But I've taken that bus twice and both times it does NOT turn left there.  It just keeps going straight down Vipawadi Rangsit (I think that's the name).  So I get off at IT Square and walk until I find a motorbike.  I'm baffled that every post says it turns left, and even the official bus route map shows it.  But it never turns left for me.

I haven't tried bus #166 from Victory Monument.  Again, I'm getting conflicting information.  People are saying the bus goes straight to Building B of the Government Complex.  Perfect!  But the official bus route map just shows the bus passing the Government Complex, not actually entering it.  Anyone ever taken this bus before?

FYI future person thinking to take bus #166, there are two versions of this bus at Victory Monument, so be sure to take the right one.

Yes, I know you can take a taxi.