877-247-3935

there is a charge on my card from USA Grant with this phone number.

YourUSAGrant
The company runs a spammer scammer website to collect information that is sold to a 3rd Party.
The persons calling you are from a 3rd party telephone solictor boiler room located in Manilla Phillipines.

You may have inadvertently entered information on its website which was collected and unfortunately sold to lots of companies.
The website is listed as follows:
Website: http://www.grantresearchguide.com

The name of the Company and address are listed below:
Grant Instructor
5348 Vegas Drive, Suite 866
Las Vegas, NV 89109

The above address is ONLY a mail drop.
The owner of the mail drop that rents mail boxes to this scammer and other scammers like this company is:
John Vanhara, President
EastBiz.com, Inc d/b/a
www.IncParadise.com
5348 Vegas Dr.
Las Vegas, NV 89108

Contact numbers to the greedy bugger that rent to scammers: main number:
702-871-8678, John's number (702) 296-0212. Office Manager, Natasha: 702-336-3193

WHAT CAN YOU DO...Perhaps send them the same spam you get.
Enter the company info on both companies listed everywhere possible...don't forget the contact telephone numbers.
Ultimately perhaps the mailbox service will be more careful to rent to legitimate companies that don't pester people and annoy persons to change their phone numbers.

THEN, file formal compalinst with government agencies.

It also a good idea to file a formal complaint with the FCC for violating the Do Not Call policy and engaging dialing equipment.

http://www.complaintsboard.com/complaints/grant-research-guide-c159562.html