a mistake on my part

Dear Mr Lord Porch,

My apologies, I fear that may have been a mistake on my part. Having sent the money my next port of call was the Spar next door and I wrote a shopping list on the Money Gram receipt and that may have confused things.
I have had a closer look and it is indeed 8 numbers, the 01 at the end can be ignored, it was actually the first 2 letters of “Olive oil”.
Has the money not been delivered yet? Do let me know and I shall return to the Post Office and ask Mr McDonald what is going on.

Kind Regards,