no it was sent to me by them am i in trouble?
To save any trouble, it would be easy for you to name them "bottle-type leads" and "dung-type leads", that would even be paying Atomic a compliment by word association.
I doubt if you're in trouble, why threaten, when it is so easy to see a solicitor and have him forward a correctly worded letter?
Atomic presumably don't have any legal right to the name.
Next thing you know, you won't be able to call a ballpoint pen a "biro".
....and just to cover my own @rse, this is only an opinion and is not legally binding in any way whatsoever.