Orange signal

I have a mobile phone (PAYG) with Orange. Various things about it bother me, not least that I can get barely any signal in my bedroom in the new house. (I had trouble in the old house, but gettng close to the window helped there. Not so here.) I have had to have bothersome phone conversations in the attic or on the stairs this week, and in order to receive calls I am leaving my phone on a window ledge outside my room (indoors, I hasten to add) and hoping I will hear it ring. This is far from ideal, but I'm not sure what to do about it. Is there anything I can do? Would something like this signal booster actually help?

Of course, I might give up on Orange anyway unless they can do me a really good deal with a better plan, as I am spending way over the odds on the phone now. But how do I know any other provider would have better coverage here?

More phone trivia

I am looking into changing my phone tariff as I am on an extortionate legacy PAYG plan which is costing me enormous amounts of money. But looking at the tariffs offered by O2, Orange, Vodafone etc., they *all* seem to be completely extortionate. Orange charges 35p/minute to non-Orange mobiles. O2 charges 20p to any UK mobile. And that's on top of paying them £20/month or more for some piddly free minutes. It's crazy, and it's making me want to give up on having a phone at all because I don't know how I can afford this. I have no idea how to compare these deals properly, and it's all hideously over-priced and stressful. How do people manage this stuff? How do I know what is good?