the process takes a way too long, at first you need to wait for the invitation for something like 2 months at its best, then for the test - other 2 months, and then (if you are unlucky one) - silence. no point to even try and contact hr, they don't bother to reply. anyway, I had this interview 3 years ago, and it seems they still trying to find since the vacancy always gets back relisted every 1 - 3 months.