what is this songg.. (indie/pop fans?)?

i was shopping the other day when i heard this song play in topshop

it was pretty new and i had heard it before but i just don't know what its called or who its by!?

its really bugging me and its got quite an upbeat catchy tune and sounds pretty indyishh

i can only remember a few lyrics which are from the chorus (i think..)

"dont you ever come back, dont you ever come"

and.."dont go off for changes, does it mean anything- what you doing to me"

^^ there more or less what i heard

what is the song cause i really like it but i dont have a clue what its callledd?!

thankss x