Help Needed With Credit Card Fraud

gettingthere28

My LTSB Amex card has been a victim of Fraud (Gods knows how they got the details), anyway phoned up on Monday and cards cancelled and replacements ordered, also told a letter of declaration sent, told what the transactions but they were only at the pending stage, so though that was okay.

Yesterday another £1019 came of for a Railway company in Australia ! (Not one of the pending ones I was told about), so phoned them back and got told they would get that passed on and not to worry !.

Questions are....

1) How long does this letter of declaration normally take to come ?.
2) The first lot of fraudulent transactions have never came of the account but still seem to be included (Held) in the available balance (Which is currently £1075DR).
3) The train one that was posted to the account and they have passed on will that be removed now or do I have to wait until the complete the investigation ?, and how long does this normally take ?.
4) How on earth could they allow all those transactions which would have taken me almost £1100 over my limit in the first place ?.

Thanks