SOAP Function Selection

/*Using the PHP SoapClient, the WSDL File: http://test.dtagent.net/dtx/dtexchange.asmx?WSDL is returning these results with the $objSoap->__getFunctions();Array(    [0] => SellGXResponse SellGX(SellGX $parameters)    [1] => PlaceResponse Place(Place $parameters)    [2] => DupeCheckResponse DupeCheck(DupeCheck $parameters)    [3] => SellGXResponse SellGX(SellGX $parameters)    [4] => PlaceResponse Place(Place $parameters)    [5] => DupeCheckResponse DupeCheck(DupeCheck $parameters)    [6] => string SellGX(string $User, string $Password, string $Message, string $DebugMode)    [7] => PostResponse Place(string $generatorID, string $password, string $leadID, string $firstName, string $lastName, string $address, string $address2, string $city, string $state, string $zipCode, string $homePhone, string $workPhone, string $workPhoneExt, string $mobilePhone, string $email, string $birthDate, string $ssn, string $gender, string $grossMonthlyIncome, string $residence, string $yearsAtResidence, string $monthsAtResidence, string $residenceMonthlyPayment, string $employer, string $employerPhone, string $jobTitle, string $yearsAtEmployer, string $monthsAtEmployer, string $ipAddress, string $cosignerAvailable, string $bankruptcy, string $creditAuthorization, string $forwardApplicationAuthorization, string $specialOffersOptIn)    [8] => string DupeCheck(string $User, string $Password, string $Message, string $DebugMode))The difficulty I'm running into is that I need to tell the soap object which function to use (There are three entries for the function SellGX() using __soapCall(). Anyone know how I can do that?*/