Poor service delivery

I signed up with this company a couple of months ago. Free internet for seven days. Paid for the rest of the month and suddenly I was cut because I used up R250-00 worth of data in one week. I am really in need of internet access and decided to give it another go. but, to my dismay, my access was cut about four days before month-end of June 2019. I made the payment on the 3rd of July but am still without internet as I get the message that my profile is invalid. I received an email: Make the APN axxess but make sure it is small letters. Still no internet.