United Sample (survey company) deleted my account

Need a help with survey company United Sample.

In year 2008 they contacted me to promote they surveys on my money talking website (forum).
I was promoting them in one special topic where i post links to surveys which they provide me on my United Sample Dashboard.

2 Months ago they deleted my account without previously contacting me why they did that. I have contact them and they have say that im not allowed to post direct links to surveys and that i need to use banners only.
But when they contacted me first time in year 2008 they send me this:
1 - You invite people on your site to join our research panel via banner,
button, email or article. We take your audience directly into our survey
router so they may take a survey and earn the $5 reward in their account (we
pay you $1 to 4 based on the complexity of the survey). We tag all people
with your code upon sign up and provide you with 20% revenue share on their
lifetime activity with us. We will send them invitations every time a
project that matches their demographics comes up (as often as every other
day). They will be paid for all the projects they participate in whether
online focus groups or online surveys.

2 - We approach you for help with specific projects (e.g. a business
executive study for the Pacific Rim). You promote the special project via
banner, button email or article, and then we pay you a set agreed upon
amount per action.

Articles can only be posts on a forum, IMO.

Anyway they tell me to remove all links from forum and that they will reactivate me, i did that, but instead of reactivating me i got post from FEDEX with a book where they links are posted, but when visiting that links i only see missing page (since i removed them).

They send me paper with state that i have 10 days to respond from they attorney Matthew S. Mazza. other way i will be sued for damages caused trademark infringement and loss of clientele.

Now i ask anyone who know how to deal with this, what i need to do?
Contact that lawyer?

P.S.S. i had around 50$ on they account and have 150 members signed under my affiliate link.
Im from Croatia and they are from USA. Im 100% sure i cant sue them, but if you know if there are people in same situation as i m, maybe i could help someone whos in USA and will sue them. I have all emails from them and all proofs.

Thanks

 

Looks like i posted info about how much will they earn if they do a survey and that is the reason they delete me... Well they could explain to me that this is info that i should not give.

And why they give me that info if they didnt want me to post?

Well anyway... looks like my account and funds are lost here.