Basic Y Level Tunnel Mining

I have been trying to get this bug-proof for almost a week. No luck, but here's everything working except the Y level for the return on the way up. Assistance welcome and enjoy!

function Mine(x)
for i = 1, x do
turtle.dig()
turtle.forward()
turtle.turnLeft()
turtle.dig()
turtle.digUp()
turtle.up()
turtle.dig()
turtle.digUp()
turtle.up()
turtle.dig()
turtle.turnRight()
turtle.turnRight()
turtle.dig()
turtle.down()
turtle.dig()
turtle.down()
turtle.dig()
turtle.down()
turtle.turnLeft()
end
end


function Down(x)
for i = 1, x do
turtle.digDown()
turtle.down()
end
end


function Up(x)
for i = 1, x do
turtle.up()
end
end


function Return(x)
for i = 1, x do
turtle.forward()
end
end


term.clear()
term.setCursorPos(1,1)
print("How far should I mine?")
local a = read()
term.clear()
term.setCursorPos(1,1)
print("How far down should I go?")
local b = read()
term.clear()
term.setCursorPos(1,1)
print("Mining...")
Down(b)
Mine(a)
turtle.turnLeft()
turtle.turnLeft()
Return(a)
Up(b)
turtle.turnLeft()
turtle.turnLeft()

Whats up with your mine function?
Its mining all over 0.0

The Mine() function digs out a 3x3 hole in the wall in front of the turtle and then sets it back in the same position, but 1 block forward. Unfortunately, I had to write out all of those commands at least once. Makes the code look sloppy .