Since I switched to Virgin Mobile, I have been unable to send any standard text messages at all. I can receive texts but cannot reply to any. When I try, it refuses to send and says "Not delivered" then I get a text from Virgin Media saying "You've hit your spending cap, which will reset on your next refresh." But I have unlimited texts on my contract, and have not used any because it always fails, so how can this be? I am on an iPhone XS. Any ideas?