Awsome C

...please help? I'm pretty sure it said it was free but not 100% now i'm a kid and i got frustrated after trying like 10 different ones (IQ tests) and you had to pay for all of them. So one said if i sign up for this thing it would give me the results it didn't now I change the last name and put a totally different address on the thing a fake one but it doesn't accept the address. So i change the numbers of my address around and still doesn't give me the results it never would i gave up on it. My mom got the magazine and checked there is no number on our street like the number i gave so they gave it to us. Today i got the bill hid it when i checked the mail. What should i do need advice, do i tell the truth but it might make us pay it or do i slip it into the mail and let her send a message saying they have the wrong house. But they want someone to pay for it and i don't know what they'll do to get the money can they find out it was me? Please i really don't know what to do give me some advice please.