Unauthorized withdrawals from my account

For the last two month’s xfinity Mobil has withdrawn almost 300 dollars from my account. They refunded last month only to have it happen again. I just get to speak to foreign people on the phone. Supervisors can never come to the phone. I need to speak to someone. They said they refunded my money again. That is great but because of the unauthorized withdrawals my bank account was overdrawn and the fees amounting 250 dollars for overdrawn for my regular automatic payments.