Datawind Ubislate — Not sending Product

Dear sir,
I had booked Ubislate 7+ at Data wind company before March,2012.
My booking ID is PMA5D79
As per their instruction I had sent a cheque of Rs.2999 to them.
After that I got following reply from them:
"This is to acknowledge that we have received your Cheque*/Demand Draft number 326717 of Rs2,999 of ICICI. Thank you for your payment. Your order is in process, the deliveries have been started. You will receive your UbiSlate 7+ within 15th May to 31th May."
After that I wrote so many emails, but they are not sending me my Ubislate7+ till today. They are also not lifting their phone to answer me!
Please help me in getting either my Ubislate 7+ or refund.
Thanks.