LittleApp — had purchased a dominos voucher worth 500 but voucher code is not accepted in website during transaction

Address:	Coimbatore, Tamil Nadu, 641035
Website:	Little app deal

I had purchased a dominos deal from little app of voucher worth 500 and followed their procedure for buying the deal from website using voucher code which i had recieved. But in payment section when i apply voucher code its displaying cannot redeem this code. Even the costumer care are not responsive if i try to connect. Please take measure as soon as possible