Thankyou very much for all of that advice. FYI, I spoke to...

Thankyou very much for all of that advice. FYI, I spoke to commseclast night to find out what happens if I don't have the $20k in my account on settlement day and what I was told was quite surprising - I get a $54 charge for not having the funds, but the guy at commsec pretty much said they won't go and sell the shares from under you for 4-5 days! I am happy to cop the $54 fee, but I am more happy that I have a few days for BNB to be at, near or over $1.24.
Thanks again for all your help. I feel like an idiot - the crazy thing is there may be a small chance I walk away from this F*&^ up with some $$$.