Can my boss sack me if im unable to get into work due to no transport or any form of funds?

i have been sent to different sites as i work as a relief security officer for a large company.i have been told to claim my travel back on a expenses form of which i have done,i havent yet recieved any form of travel expenses back.the other day i was told that im to go to a site,of which i couldnt get to due to no funds or transport...im now being given a disciplinary hearing.can they do that.