I hate to be this guy, however I will be right now.
Do not be an idiot and use these services. Unless this is a very old phone, you probably paid a lot of money recently to own it. If you bring it to one of these places, you are essentially throwing away any support you will ever get from Apple for this device.
Using 3rd party services voids not only your warranty with Apple, but any technical or hardware service (ex, your buttons don't work, the screen the 3rd party puts on is faulty, a speaker isn't working, ect.). You are literally SOL by doing this, and as someone who has worked with Apple in the past, they can and will tell if there is non-Apple tampering on the device.
Bring the phone to an Apple store and get it fixed. They can also tell you if it is unlocked or not.
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