Critchfield Pacific Does not pay. Honolulu HI

We had them open an account with us because they needed to have some weld testing done for procedures.  They signed a credit application and we opened an account for them.  They had 6K in work done with us over 2 months and we billed them.  its been 7 months and we cannot not get them to pay their bills.  We have called and called and when we try to talk to the president of the company he is alway in a meeting and no one in the accounts payable department will return any calls.  We will be sumiting this account to a collection agency.