Given False commitment and then not receive call

Dear sir,

I was got one voucher of giffiti technologies against purchase of OLG product. So that I used it for buy products as per attached images. But products was not good as per quality so that I want to return it. But after many calls and email sent to giffiti technologies but no one can help me and Told me false commitment and last 4 days not receive my call also. So request to help me.

Thank you
Regards
Dipak Diyora