Not able to download OS x Mountain Lion SW

I purchased OS X Mountain Lion s/w but the s/w hardly crosses 400 MB download.

When ever the s/w is being downloaded an error with retry popup appears and I hv to start all over again. My internet connection is good.

Now I got the error again becoz of which I can't see the S/W in purchase list.

Could anybody help me out with overcoming this situation?

I'm using MBP..