PayTM - Non fulfilment of service

I had ordered an an Iphone * plus ** gb and it was expected to be shipped by **th oct. According to paytm if seller fails to ship it till **th oct the order will be automatically be cancelled. I have tried to contact them a no. of times and they reply after ** hours and after **th they are not even replying. Moreover, the mode of payment was credit card and due to which I have to incur unnecessary interest payment. I requested them either to get the phone delivered from othet seller at same discoint or compensate me for not fulfilling the service and wasting my time. My money is stuck and have to buy it at a higher price than it was available earlier on other online platforms which I ignored just because of paytm reputation. I request you to get my money back and additional compensation to teach paytm a lesson as to how to treat a customer.