LittleApp — dominos voucher purchased is without balance

Address:	Kolkata, West Bengal, 700030
Website:	Littleapp

Hi i recently purchased dominos 500 voucher from little app.
But it is showing zero balance while applying dominos website.
I have already raised my concern with them but unfortunately they responded that i have used that amount.
This is very unfortunate that it happens and without any investigation they concluded wrong.
I never used it and never share the voucher with anyone.
My email saikat. [protected]@gmail.com
Do the needful.