They Keep Charging My Credit Card. What Can I Do?

The company's name is FindaHauler.com and is also under the name Nexmation, LLC. For the past 4 months they keep charging my prepaid debit card for $20. I have told them to stop via email and that I don't use their services. I've emailed them through their website and found the owner's email. They don't respond. They're trying to charge my card AGAIN. It declines because I don't have the $20 on card. When my husband's check gets direct deposited, they take the $20. They always try every day at 1 a.m. and 6 a.m. until they finally get it. What can I do to make them stop?? So far they owe me $100. Last month, they took $20 from my card on the same day. Not sure why the double charge. We are so very financial struggling right now and I can't figure out how to make them stop.