Late filing of 108

Hi Friends,

Need a help from you.

            I was late by 20 days in filing Form 108.  The reason Being My auditor was out of Station.

My Query is :-

1. In condonation letter can I mention the delay is due to auditor (or) any other reason on my part.
2. Is Auditor sign necessary in the condonation letter.
3. The late fee of 100/- to whom it should be payable.

Please kindly help me Friends. Some of them are saying auditor sign in necessary some are saying it is not necessary I am totally confused.