HDFC Bank — Customer care lie about offers

I had to purchase and electronic device so i called and iquired about the emi option to hdfc credit card customer case on 3rd may 2016, they confirmed me that i can go ahead with the purchase and they would convert it to emi as i have the offer, , after i did the purchase i called them again to covert the amount to emi, however they ask me to call after 2 days as the pay will reflect only then, . Today 6th may when i called they just told that i dont have emi offer and it is expired .

I proceeded with hdfc credit card only after they confirmed i have emi option available .
The customer care lady asked me to call after 2 days and promised they would do after 2 days .
Now when the payment is done they say i dont have any such offer .