>“At this stage the Council has not calculated the final costs of processing your application.  Should the final costs exceed the deposit already paid, then as previously advised, you will be invoiced separately for these costs.  Should the final costs be less than the deposit already paid, then you will receive a refund.  Where the costs are equal to the deposit already paid, no further action is required.  You will receive a letter shortly regarding the final costs of processing your application.“

How about:

“We will contact you shortly with the final costs of processing your application, either invoicing you or issuing a credit for the difference between your deposit and the final costs”.

“Where the costs are equal to the deposit already paid, no further action is required”

WTF?