Sending an email asking to participate in an ipo then sending another stating the amount u want might or could constitute an order to buy x amount of shares in x ipo .
If it is only small dollars then forget it but if it is big bucks then find a solicitor . Lawyers aren't cheap and start at around 300 bucks an hr and probably more for an expert in that field .
I'd be also requesting a copy of the taped conversation with your broker so u will need to know the date and approximate time of your conversation .