iPhone 5 internal speaker not working

The title says it all. I've had the phone since November. It's in perfect condition. I used it this morning it was fine. Then in the afternoon I tried making calls and the internal speaker won't work.

So I know it's under warranty but I have 2 questions

1) I live 6hrs from an apple store. Can I ring them up get an order number and post it to them?

2) will the fix it or give me a new phone?

Thanks.

I'll try resorting it tonight and see if that does anything.