Fibrestream is no good business

In the beginning of June 2020, I app**** for WIFI with FIBRESTREAM. They told me if I make a payment that same day, they will install WIFI within 7 days. That same day I made the payment they demanded but after a week they still did not do the installation and I had to wait another week. 10 Days after installation they sent me a mail saying I am in arrears on my account. When I queried it they responded that the arrears was for a full months rental. I ask but how can they charge me for a full month while I had WIFI for only 10 days. They did not respond and I am still waiting for an answer