this number called me n when i picked up they hung up and when i called back a recording said it could not process my number and to contact customer service.  how can i get customer service if i dont have any information?

please find out  who this is?

They have called my cell about 17 times in the last day. Often 15 minutes apart. When I answer, there is no one there, and they hang up.

Calling them is futile, as they refer to a "customer service number," but they do not give out that customer service number.

I tried to email them at contact@ITLtd.net, but they still have not stopped calling.
Caller: ITLtd.net
Call Type: Telemarketer

I have no idea who this caller is.  Has called 4 times already.  I have caller id and it just states out of area.
I have a new unlisted number and wonder how these people get your number.

My ID says Seattle and they call here all the time and hang up.  They are a collection agency I think.