Paypal sent a collections notice…what?

Hi Guys,

 

I received a letter from a collections agent saying I owe them about $600. At one point I sold a phone on ebay, I shipped the phone out but mistakenly did not request a tracking #. The buyer said he never received the phone and I was told to refund the money. I was about 16 years old and the account was in my own name. What do you guys think I should do? Keep in mind that :

 

1) I was under 18 with the paypal account and ebay account in my own name and not someone elses. Aren’t all contracts with minors void?

 

2) I sent the phone out and am not a thief.

 

3) This was over 5 years ago.

 

Thank you for any help on what I should do so that this debt does not go on my credit report. If I have to pay it I will but just sucks that I really did send the phone out but had no way to prove it.