Great song.
I'm pretty sure this is right, if you play along with the song it sounds perfect

For the Csus4 part, I just add my pinky for a few beats, then kind of palm mute it, then back to C

C (x32010@1)Csus4Dm  G (320003@1) F (133211@1)e|-0---0---1---3---1-|  
B|-1---1---3---3---1-|  
G|-0---0---2---0---2-|
D|-2---3---0---0---3-|  
A|-3---3---0---2---3-| 
E|-0---0---0---3---1-|

GARRETT

C (x32010@1)      Csus4C     CCsus4 CI'm (x32010@1)gonna wear you down

C (x32010@1)      Csus4C     CCsus4 CI'm (x32010@1)gonna make you see

Dm (xx0231@1)              F (133211@1)              CCsus4 CI'm (x32010@1)gonna get to you, you're gonna give in to me

C (x32010@1)       Csus4C    CCsus4 C (x32010@1)I'm gonna start a fire

C (x32010@1)       Csus4C    CCsus4 CYou're (x32010@1)gonna feel the heat

Dm (xx0231@1)                F (133211@1)         CCsus4 CI'm (x32010@1)gonna burn for you, you're gonna melt for me

BOTH

G (320003@1)             FCome (133211@1)on, come on

G (320003@1)         FInto (133211@1)my arms, come on

C Csus4 C
Give in to me

LEIGHTON

C (x32010@1)      Csus4C     CCsus4 CYou're (x32010@1)gonna take my hand

C (x32010@1)      Csus4C     CCsus4 CWhisper (x32010@1)the sweetest words

Dm (xx0231@1)           F (133211@1)                  CCsus4 CAnd (x32010@1)if you're ever sad, I'll make you laugh, I'll chase the hurt

BOTH

C (x32010@1)      Csus4C     CCsus4 CMy (x32010@1)heart is set on you

C (x32010@1)      Csus4C     CCsus4 CI (x32010@1)don't want no one else

Dm (xx0231@1)              F (133211@1)              C (x32010@1)Csus4 (x33010@1)CAnd (x32010@1)if you don't want me, I guess I'll be all by myself

G (320003@1)           FCome (133211@1)on, come on

G (320003@1)          FInto (133211@1)my arms, come on

C (x32010@1)    Csus4C
Give in to me

LEIGHTON

G (320003@1)    C (x32010@1)     FI'll (133211@1)use my eyes to draw you in

G (320003@1)    C (x32010@1)     FUntil (133211@1)I'm under your skin

G (320003@1)          C (x32010@1)       G (320003@1)     CI'll (x32010@1)use my lips, I'll use my arms

FCome (133211@1)on, come on, come on
  
      C (x32010@1)Csus4 (x33010@1)C (x32010@1)      
Give in to me

BOTH

C  Csus4 C
Give in to me

CGive (x32010@1)in to me