It is a larger area then Jomtien Complex.
You should know where to go, as it are all small shops from the outside, with no masseurs outside.
Closest to BTS Saphan Kwai are Phetboy Spa and K Man Spa. Both tested and rooms are fine.
A 10-15 minute walk are several massage places, often reffered to as "Inthramara" because sois are named liked that: One Spa, BT Massage, Phoenix Spa, 27M Massage, ...
You can follow the shops on Twitter/X and contact them on Line.
Accomodation in this area I can recommend is Blu 395. It's a building with serviced condos, not a hotel.
On Instagram, you could also look for 483 Massage, as they have some nice twinks, but I never have been there as it is further away.