Mobile Internet concerns

The mobile Internet is great when it works properly,  but when it goes wrong!

I get endless scam calls, the latest claimed to be from the Tesco billing department,  the said that they were upgrading their sim cards from 4G to 5G and I needed to..... I ended the call.  I'm not with Tesco mobile or have any account with Tesco. So obviously a scam call.

Banking app.  Failed to open this morning.  Just gave an error message that they are fixing the error and to try again later. 

I tried to top up my mobile online, after several attempts it showed me an another account claiming that I owed over £286 with payment due 2 July 2026.  I tried to find out what this amount was for, the app gave an error message and crashed out.