No real customer service, incompetent and Abwimmeltaktik with complaints

Can actually not even awarded a star.
After about 2 months use the SIM card was faulty, it did not work well in other simlockfreien phones. After 4 emails with the so-called customer service I should still pay 14.99 for a replacement card. On my repeated reference to the statutory warranty period of 6 months was not responding. It came Congstar-mails with suggestions like trying out in other phones and SIM-lock, even though I had this already described.
After Find in Congstar Customer Forum to me it has become clear that other customers were similarly treated with the same problem and only through time-consuming multiple communication after long weeks free replacement cards were given (which failed again often after a short time).
NEVER AGAIN CONGSTAR. I think my remaining balance I let expire and look around for a customer-friendly suppliers.