Eeep, AmateurSwami! Mine did that in the beginning, until I rang and explained it really was me doing all the betting transactions.
I learned something interesting about Betfair tonight. I topped up my balance to the exact amount I needed for a lay. Call it £11.32. When I entered the stake, the liability showed as planned - £11.32.
However, when I went to place the bet, I got a message telling me that I either didn't have enough in my balance to make the lay (nope, I did have enough - exactly enough) OR that I'd exceeded my exposure limit.
By Betfair's own help pages, the exposure limit is set at a default of £5000, so you can't exceed that in bets you're waiting to settle. I didn't even have £100 of open bets, so there was an error somewhere.
I used the chat, and they got me to try adjusting the stake by -1p. I did, and it went through. Soooo... apparently Betfair rounds up your exposure. So don't make lay bets that will eat up the entirety of your balance, because they won't go through - you need at least 1p more.
Weird, not really important and easy to avoid, but I thought it was worth mentioning.