Rescue plainly sucks on ELO, I tried every single combination I could and couldn't get much past 1250...their best cards are perma-banned, and they suffer a lot against SoA and SoB (and if you see that Gheist, Piranas and Nightmare are used quite a lot, you have a big problem here).
With those 17k have you can build yourself a pretty solid deck, that can easily get to 1300+
Jeto, Noodile, Rico, Yookie, Sigma, Jautya, Uranus, Petra
(Just out of my head, some cards I always see when 1300)
Yes it can be frustrating.
i reached 1297 once, trying for more creds and the mission.
then crashed to 1210.
my advice is to know the weekly metagame and focus.
it usually takes my an hour to get through 1100 and a few days to improve (or lower again).. lol.