Rain disconnects my WIFI every 3 days and requires a payment.

My payment date is the 1st of the month and I made a payment the day before(31st). There was no problem at first, I had good internet connection. It's only a couple of days later that they're sending me SMS informing me that I missed my payment on the first and I need to pay the full monthly payment. I called their call center and they acknowledged the error and fixed the issue. I had connection for about 3 days, and the SMS again and the 5G WiFi was disconnected. I called again today and the consultant tells me that I need to pay the full amount again, for the second time in one month in order for the WiFi connection to be restored.