False Advertising

I app**** for rain after an ad of one month free. But when I called to pause my services, it became very clear that there was no month that was free because I am billed backwards. For all the monthly debits that have gone off my account. it turns out that when I pay in July end of the month , for example, I am not paying for my usage in July but that of the month of June and so on and so forth. After multiple communications with the company this still does not make sense to me because when I started using the services, I made a payment before I even received the router, nothing is making sense to me at all. So how I see it this was false advertising.