Been with them for a year, never had a single call or junk mail from them.
Just a real bad signal where I live. And internet on mobile going off, about 2 or 3 times a week.
But to be honest I think that's my phone, as it keeps jumping of the network, and I have to re-register it.
Am on sim only at £15 a month for unlimited text, calls, internet, I think that's brilliant.