Hi Sammy,
If the money has been withdrawn from your bank account then that is one good news. I think you need to wait at least 6-8 weeks in the most extreme cases for an acknowledgement letter. If after 8 weeks, you still haven't received one, then you should call the home office and make an enquiry. I received my letter within 2 weeks. But do not worry, if they have taken the money from your account, then it means they are processing your application. Good Luck!

Thank  you   Mohammad  Amir .It  is  so  kind  of  you  .  Many  thanks  for  your  reply .

Please  Mr Mohammad Amir  ,  i  have  an  urgent  enquiry  ,  could  you  help  me  please ?  I sent  my  application  for   naturalisation  on  1/01/ 2010  and  the  fees  money  was  withdrawn  of  my  bank  account   but  the  problem  that  i  did  not  receive  any  acknowledge  letter  of  UK Border  Agency .  What i  have  to  do ?  Any  reply  please . Many  thanks  to  this  website .