Airtel — fastag

I have ordered a fast tag from airtel's payments bank. I had ordered on december 11th and it was dispatched on december 18th and was supposed to be delivered within 7-8 working days from the date of dispatch. It's already been a month now and i have not yet received the fastag. Despite putting so many mails, phone calls and even visiting their office, i haven't still received it till date and they haven't been giving proper info with regard to status of the fastag.in one of the emails they had sent a tracking number but however on tracking there was no info available whatsoever. If they can't deliver it atleast they can give an option to cancel the order so that i can arrange for buying fasttag elsewhere. This is just so annoying. Worst service ever from airtel. Very disappointed.