Composer Compatibility Issue

[kojoduncan]

I'm not sure if these errors are related but I get composer errors when I require constantcontact/constantcontact ^2.1. It says it require guzzlehttp 5.1.0. However the build of guzzlehttp is incompatible with other requirements in my composer.json file. I'm currently running constantcontact development build which triggers no compatibility errors in composer but I'm getting the errors below when I try any functions in constant contact.

[24-Oct-2016 06:45:03 America/Detroit] PHP Warning:  json_encode() expects at most 2 parameters, 3 given in vendor/guzzlehttp/guzzle/src/functions.php on line 322

[24-Oct-2016 06:45:03 America/Detroit] PHP Fatal error:  Call to undefined function GuzzleHttp\Handler\curl_reset() in vendor/guzzlehttp/guzzle/src/Handler/CurlFactory.php on line 78

Any help?

Thank you