When UKBA send the acknowledgement Letter. Please help!

I want to know when the UKBA send the acknowledgement letter, when they received the application, or after ducting the application fee? I checked with my friends and all got it after ducting the payment.

Actually I got the acknowledgement letter from UKBA and after few days got email from my case worker regarding some explanations. Before my reply, he sent me another email to tell me that my application rejected because of non payment and they are not able to get payment from my credit card.

My bank said there is no attempt for payment against my card; I feel there is some error at UKBA end. Could you please guide what should I do, Can you please confirm when you guys get your approval letters, after ducting the payment or at receiving the application.

Thanks for the help