Iphone 4 replacement

Hello i have had my white iphone 4 16gb just a few days over a month and i have many problems them being

- Everynow and then apps i load up decide to just crash and take me back to home screen

- I could be watching a video on youtube and half way through internet disconnects but my laptop or anything else using internet doesnt

- In a call after about 10-15 mins the person i have called goes all crackly and really hard to hear making me call back for it to happen again

- and everynow and then my headphone jack. Decides it wants to make everything really quite even with voloume high

And as i said its just over a month old and my sister has had over 4 replacements and as i live quite far from my apple shop and i look after my disabled mum i have hardly anytime to go up there so if i tell them this and ask polite would they be able to give me a new one what do you think?

Many thanks

Dan