about repairing

Hello.this is Yurina.

my iphone dosen't work well.

the battery broken...

i am for sure about it.

and i want to know it is only battery problem or any other else.

so i want to bring it and discuss about that.

do i need to make reservation?

or i just visit there??

also i want to use apple care.

can i use apple care at phone repair shop around there?

or i can use it at only apple store?

Thank you.