Fradulent access to my account from third part claiming to run the corporate account

I received multiple communications from a company called AsmartIt from numbers [Edited: "Personal Information"], [Edited: "Personal Information"] claiming to give a discount of 30% on my existing plans since they had a corporate account with Xfinity. They fraudulently accessed my profile to change my plan and send me a new modem.They were able to play around with my auto pay card and add their own card for the payment.

They promised to take care of the bill for 15 month if I pay them 12 month money .so I happend to transfer the 700$ using zelle.they added the card and made a payment to my Xfinity account to increase my confidence in them. A few days later I realized that the payment they made to my account was rejected by Xfinity. They are not responding to my calls anymore.

I am very sure that I did not pass any personal details or pass code to them so that they can manipulate my account.

This looks like more of a security breach from Comcast side .Since only authorized person can access the account I happend to trust this person and made a payment 

I would like Comcast to review and refund my money as a security breach compensation. 

Please reach out to me for any more details.I will be happy to assist you further and help investigate it

Regards

Nitesh