Do I need to fill out a W-9 form if I'm not getting paid?

I'm a private music instructor who works with several other instructors in a private studio. My students pay me directly, writing checks out to my name, or paying me in cash or via credit card payments which I take with my iPhone. I pay the studio owners a set amount of rent per student, and over the past 8 years we have all been happy with this very informal arrangement without resorting to any type of contract outside of a verbal agreement. I file my own taxes, and report the income I make as a teacher as self-employment, I do not receive any payment from the studio in any way. Recently my associates have approached me and demanded that I provide them with a W-9 form, insisting that I have to fill it out to prove that I'm a citizen legally able to work in the United States in accordance with their incorporated status. My reasoning for denying them a W-9 form is that I'm not an employee, and do not receive any payment or wages from their corporation, and am therefore not liable to them for any sort of tax culpability.Am i correct in assuming this, or are they correct?

I have lost my iPhone and have no insurance?

My contract is sim only so my network will not replace my phone, I've had it less then a month and stupidly not put insurance on it, what should I do, it's on finance so I still have to make another 20 payments on it regardless of whether I have it or not.

How to unlock my iphone? Don't know the password?

So then i had to restore it. Which took 5 hours to load. I had to do all that cause my i accidentally changed my password and i have no idea what it was. But then after waiting 5 hrs, my phone is still locked. I don't know what to do! I tried a few passwords but nothing works! Someone please help me! I'm so nervous cause i just got it about a week ago!

I can't get pictures on my iPhone?

I always can get pictures when they're texted to me, but recently, it shows that I have a picture message & it shows the blue arrow next to the picture, but when I click on it, it just shows a black screen. I get pictures in iMessage but not text message. What do I do?

What stores sell iPhone cases?

Hi, not online stores but any other retailer.
I need a long list of retailers
Can you please list some places that sell iPhone cases? Big and small businesses.
(not obvious places like best buy or Walmart)