I pleaded guilty to speeding but they gave my 6 points, i will now lose my license. Can i change my plea?

I got caught speeding doing 48 in a 30, i got a letter from court asking for my plea. i pleaded guilty thinking i would get �60 fine and three points but they gave me �140 fine and 6 points, i will now lose my license. Is there anything i can do?? Any help would be great thanks.