Cannot get my refund
 

I have cancelled my Lufthansa flight ticket on 7th July 2016, and now after 40 days I haven’t got my refund yet. When I cancelled it was mentioned that I will get my refund within a week. I called several times, and each time; I was promised that I will get my refund within next few days. Last Friday (12th August) I have been promised by Lufthansa that I will get my refund on Monday 15th August for sure 100%!!! Again yesterday after waiting 15 minutes on phone, I have been promised that I will get the refund same day, and I will be informed by phone call that the amount is paid.
But still haven't got it yet, and when I called again Lufthansa why I haven't got my refund, they told me to wait for next few days again!!!!