Unreachable manager after taking ineffective loan and rude sales agent

Unreachable manager after taking ineffective loan and rude sales agent. When I ask , does the loan become effective after first debit order,no response. When reaching out, am told she's works even on Saturday and am impatient. I explained to the agent that I too work on weekends but I don't remind my clients like am doing them a favour. Am still within the 7 day cancellation but the agent says me cancelling it's gonna affect her but me, meaning there's a hidden clause that wasn't disclosed to me. Am told I need to send the loan agreement to the institution where am studying but the institution is closed. Now am left hanging. Please kindly help with the cancellation. How do I pay for a service not rendered?