Thanks for your response.
I reached to examity desk via online chat facility but their representative asked me to "check with the certifier dynatrace as they do not formulate the charges and is taken care by dynatrace".
However, I rescheduled the exam by paying 35$ (30$ Late fees + 5$ Tax) and got to know from colleagues that, we have to re-schedule the exam at least 1
week before the actual exam date.
I saw this in a recent email, but I'm not sure whether this is relevant to any and all exams or only to the specific one I received the email for:
Please note if you need to reschedule your exam please use the reschedule option not cancel. If you cancel it will cancel the exam and considers the code used and it will not work again. There is a fee if you reschedule in less than 24 hours before the currently scheduled exam time.