The only way I could find the right link to purchase a ticket for the Spurs match was to click on the "All" link under the "Upcoming matches" heading on the "Ticket Home" page. Clicking on "Away tickets" doesn't give you an option to buy the Spurs ticket! I wasted a lot of time and effort trying to buy the ticket and hope this will stop you doing so as well. Whilst I'm moaning - why can't the system keep your debit card details? And why not pay by PayPal - much simpler?
Cant blame the club as it's Ticketmaster that does them now. But I now what you mean, I gave up trying on Liverpool tickets saying I could get one but not the two other tickets that I wanted.