You can't say no to Lucid

I received a phone call from 5 consultants and a manager explicitly told them I was NOT interested in their products. I aslo asked then NOT to debit me. Each consultant promised letters confirming such and I never received them. When i call there is answer only an automated menu. They proceeded to debit me. I have not only incurred cost to process the debit with no funds in the account, I will now have to incur additional costs to call them to delete the debit and bank fees to reverse this. Please can anyone ehlp me be assured this will NOT happen again, becasue I do not KNOW what to do. i did not sign a contract, and i was pretty i did not want ANY of their services