Problems with porting the game to Bigpoint

Question

Game development

1. request portal.sendUserMail returns "Got wrong authHash or request timed out"
parameters passed - {"jsonrpc":"2.0","method":"portal.sendUserMail","params"1802,1040,105,3651," ru",{"nick":"DevLoungeTest_4eb4b1f86949c7.90290610"},1320921689],"id":1}
authTimestamp - time();
authHash - strtolower(md5(strtolower($request.'5c4ed5e090c160dfd3e634958c9efbe2')));
the request is made to portal-api.sandbox.bigpoint.net/xmlrpc/?authHash= $authHash

Maybe someone has a working piece of code? I've run out of ideas, and the project is stalling because of this...

2. payment api at devlounge.bigpoint.com/techsetupapis/payment/projectId/1040 returns "Antwort:n" for any request. and should be, in theory, a response from the server.

Technical support practically does not communicate with developers, so nothing can be achieved from them. Maybe someone worked with them or knows someone who can advise?