I am pleased to be able to assist you today.
You are already taking the correct steps in applying to amend the claim to reflect the correct Defendant. Form N244 is the correct form to use in that regard. A fee of £155 is payable on such applications and your cheque should be sent to the Court along with three copies of your application. The cheque should be made out in favour of "HMCTS" or "Her Majesty's Courts & Tribunals Service" if there is room on the cheque face.
A Fee account number is ***** used by legal professionals if they pay fees direct through a central account. It is of no relevance to you in this instance.
The reference to a Warrant Number may be important if you have receive a warrant to enforce from the Court. The Sherriffs Office might be able to provide you with that if that is the enforcement route they have taken on your behalf. If not, it is, again, of no relevance.
As long as you give the Application Notice the correct identification in terms of Claimant and Defendant (and these should be the details from the original claim and not the ones to want to amend to), then the application will be capable of being recognised by the Court staff. Please ensure that you quote the correct Court Case number ***** the top right of the document.
The New Defendant's details should be filled in towards the bottom of the first page where the form asks for "Parties to be served" at 9, and for their address at 9a. This is where you add in the new Defendant's details and address.
I hope that this is of assistance and I wish you well with your application.
Please do not forget to rate my reply so that I can close your question and receive my fee.