iphone 3 credit lost after software download

I have recently downloaded the new software for iphone. I had over £23 in credit which has GONE!! I have now been asked to re enter my bank details inc security code for payment of an app and have been advised that my bank security code is wrong! It's not. I also have an ipad that I sync which has created a conflict of sorts. How can I retrieve my money please?
p.s. The missing credit is not on my ipad. Thanks

 

I had an iTunes voucher for £25 which I redeemed in my iTunes a/c so each time I purchase an app the cost is deducted. So the credit is used for buying apps or music. Now it's gone.

 

I had a problem contacting Apple online so I decided to ask for assistance here before trying them again. With previous issues I have found this Forum more helpful than Apple!

 

I'll do that, thanks. But the credit has gone somewhere!

 

I will. Thanks.

 

I have looked at my account on iTunes and there is no sign of my credit.
I clicked 'Report Problem' and nothing happened. I have synced again but still no luck. I have also 'lost' my credit on my iPad. Ridiculous. I will call Apple later but not holding my breath as in this country (UK) the staff are not very helpful and quite patronising. I'm not good with technical issues.