Vantage Funding called numerous times never answered withdrew money and balance was negative took thirty out Internet

I received numerous called from 1-888-235-3097 and I answered once and they hung up. I never answered my phone after that. They eventually quit calling and I didn't think anything of it, until I withdrew money out of my checking account.
I always get receipts of any bank transactions. When I looked at my balance and it was negative, I began to make phone calls to my bank. When I found out that a check for $30.00 was electronically done, I knew that was incorrect. I asked what the name was on the check, I went on-line to get more information.
I am going to my bank in the morning and file a letter of dispute. I am a single mom and I really live paycheck to paycheck and this has caused a mess. How can this company continue to do this?