Would a keylogger still be active if I upgrade my iphone?

I wondered whether anyone can help?

About 18 months ago my itunes account was hacked and I had about $200 worth of apps purchased using my credit card. Mostly with Chinese names. Luckily my bank refunded the money. However, when I reset the password the same thing happened again. Someone had also authorised some other PCs to use my itunes account. In the end I simply deleted my credit card from the account and just haven't been able to use it to purchase music or apps since. Which is very irritating.

I had no idea how it could have happened but then read about keyloggers and that seemed to me to be the most logical explanation. Does anyone know whether this is likely or whether there could be another explanation? Also how could it have got on my iphone in the first place?

I became even more suspicious when my facebook account was accessed without my permission by someone at a pc in taiwan last week. As I have the facebook app on my iphone I can only assume they got the password from when I entered it on the phone.

So if it is a key logger is there any way I can find out for sure and get rid of it?

And if I upgrade my iphone 3GS to a new iphone 4 would I still have the same problem i.e. is the key logger just on my phone or would it be transferred to the new iphone when I synched it with my itunes account? I obviously don't want to sign up for another 24 month contract then find I can't use itunes or the appstore all over again.

BTW my iphone has not been jailbroken.

Thanks for any help!