Why is the link on the MTN mifi and HyNetflex not working when you try to buy data?

I got data on my MTN line with the HyNetflex and tried to subscribe but the link I have been using to recharge has not been working for a couple of days. I also tried using the USSD cause I always recharge for unlimited 150GB for the month but at a certain point I get the message that no mifi consumer is attached. This is very annoying