By WiFi do you actually mean mobile data?
Can't you connect to a free WiFi local area network to get connected in order to top-up (buy a membership plan)?
E.g. in a McDonald's, library, other retail outlet etc.?
Or use a computer connected to the internet?
In the past 48 still allowed access to the 48 website even when there was no active membership plan or mobile data allowance had been used up, but maybe that no longer works?
You could enable membership plan auto-renewal so that you don't have to buy your membership plan manually.
If you need to contact 48 support about this then see the links in my signature below.
