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  Csus4 Dm  G   F 
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        Csus4 C     C Csus4 C
I'm gonna wear you down 

C        Csus4 C     C Csus4 C
I'm gonna make you see

          Dm                F                C Csus4 C
I'm gonna get to you, you're gonna give in to me

C         Csus4 C    C Csus4 C 
I'm gonna start a fire

C         Csus4 C    C Csus4 C
You're gonna feel the heat

           Dm                  F           C Csus4 C
I'm gonna burn for you, you're gonna melt for me

BOTH

G               F
Come on, come on

G           F
Into my arms, come on

           C Csus4 C
Give in to me

LEIGHTON

 
C        Csus4 C     C Csus4 C
You're gonna take my hand


C        Csus4 C     C Csus4 C
Whisper the sweetest words

              Dm             F                    C Csus4 C
And if you're ever sad, I'll make you laugh, I'll chase the hurt

BOTH


C        Csus4 C     C Csus4 C
My heart is set on you


C        Csus4 C     C Csus4 C
I don't want no one else

           Dm                F                C  Csus4  C
And if you don't want me, I guess I'll be all by myself

G             F
Come on, come on

G            F
Into my arms, come on

     C      Csus4 C
Give in to me

LEIGHTON

       G      C       F
I'll use my eyes to draw you in

G      C       F
Until I'm under your skin

G            C         G       C
I'll use my lips, I'll use my arms

      F
Come on, come on, come on
  
      C  Csus4  C        
Give in to me

BOTH

           C  Csus4 C
Give in to me

       C
Give in to me