Have you tried using the Movela web site (www.movelia.es)?

Your problem may be that your VISA card is not verified, but the website should ask before dumping your transaction.

i think i looked at that site but its in spanish isnt it? ill take another look thanks.

is Ida y vuelta a round trip?

Yes, Ida y vuelta is 'round trip'.

The English language site is: http://www.movelia.es/en/

....and the reason you HAVE to buy a bus ticket online is....? I am often baffled by people who think is it "do or die" to secure public transportation tickets while traveling a route where there is a departure every half hour.....

You don't have to purchase your tickets online, but, depending on when and where you're planning to travel, buying your ticket ahead of time is always advisable, even if it's only a few hours. Buses from Sevilla to Granada are often full at certain hours of the day and on certain days of the week. Other days there can be no problem. It's the same with buses from Donostia and Pamplona to other points on the map. Sometimes you can get lucky, other days you'll have to wait.

I guess it's okay if you have the time to waste, waiting for the next bus, but I don't mind buying my tickets ahead of time. Besides, if you wanted to catch the Supra from Madrid to Granada, there are only 4 departures/day listed on the ALSA website, two during the day, two at night, and only one departure on a Saturday.

and I am baffled why one wouldnt buy a ticket ahead of time. first of all i dont speak the language and machines even in english confuse me. my vaction time is precious to me and i like to have things ahead of time as much as possible. i dont think thats unreasonable Viajero2. thanks to those of you who were helpful.

We used ALSA 3 times while in Spain last month; great on time service (went from Bilbao to San Sebastian R/T, Santander R/T & Madrid O/W). The best option is to buy tickets from a vending machine. It has English menus, takes CC (mine was chipped with PIN), doesn't charge SC (website does) and gives a receipt.
It is possible to change or refund full price ticket but it wouldn't be very easy to do without basic knowledge of Spanish.