I need someone to post my Xero payments on account

Kind of support: Bookkeeping, Report
Accounting software: Xero
Description of support work: I need someone to make the relevant recordings in Xero for the bank receipts that I have. I am an accountant myself, and receive several of my fees as retainers. As a result I receive several "Prepayments" that need to be recorded.

I.e. I receive a retainer payment of £75 per month and Xero won't allow me to offset the monthly transactions against an annual invoices. I have to go through and enter these as Prepayments each month and then apply them against the invoices, quite annoying as this is accounting software and it doesn't allow for something that it standard within the indstry.

I have around 15 retainer payments in per month, and need them processed for September 2013 to May 2014. There are roughly 110 entries to reconcile in total.
Extra notes: