Program that can handle my customer details

I have a webhosting company and i want to ask a question.
I need a program that can handle my customer details
Like this 3 companies.
modernbill.com
ubersmith.com
phpmanager.com
Does anyone has any experience with them or recommend me any other. Also can you tell me how much it cost and if i can use 2checkout with them.
Thanks.

 

 

 

 

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