I'm sorry to learn about the problems you're experiencing at the moment. There are a few things we can check through via the community, although for an urgent response to this issue I'd recommend giving our team a call on 789 from your mobile or 0345 6000 789 from any other.
It's possible that you've exceeded your data limit, in which case you would have found it performing better today, is that the case?
If not, check our [Coverage Checker] for any problems in your local area, are you also able to clear the data from your browser? (cookies / cache). Finding out how to do this depends on your device / browser so if you want any instructions, just let me know what you're using
Sorry again for the inconvenience, we're looking forward to hearing from you