I only have debit card ,what is my options
The only option is Credit Card
You can use your debit card if it is activated for online purchases. I just used mine, a capitec card
Sometimes the debit cards do work and sometimes they don't. It is a not a reliable way to make payments. Credit card seems to be the most reliable way to make payments as they do work.
what has changed since I last topped up. Why cant I get into the top-up portal?
Nothing has changed recently.
Kindly send a screenshot of the error you are receiving when attempting to top up to firstname.lastname@example.org.