Overseas ballot unsuccessful, what next?

We've been planning our trip to see Brentford v Everton for about 9 months, and although I purchased overseas memberships and applied for ballots for the match, they were unsuccessful. Can anyone advise how to proceed to obtain tickets? I've emailed the ticket office, although they are slow to reply sometimes. Any advice is appreciated! This will, hopefully, be our first ever match, not to mention trip to London.