Ubislate 7+ tablet from datawind undelivered

I have ordered ubislate 7+ tablet online from www.Akashtablet.Com website on 03-mar-2012 and my booking ID is pm5f7934f662 and as per website details I sent cheque of rs. 99/- With cheque no : 2879 and my cheque cleared on 23-mar-2012. At the time of ordered they commit me to deliver product in april-2012 MID. But they didn't deliver me product on committed time and whenever I call them or send email about this they reply only that they will deliver me product within 15days but till date they didn't deliver the product and today also giving same answer that they will deliver product in 15days.