I can imagine your frustration. I myself never had this problem, and I have a 5mb download speed. (DSL)
For the life of me I cant think of why that game would take so long to download. People have had success using a proxy to speed up
psn store downloads. Have a look here:
My speed isnt that much faster than yours, but I never had to wait that long. Ratchet and clank: all 4 one was 15 gigs and it took me 4 hours or so. Have you called sony? Its 1-800-345-SONY.
Try the article above, and explore the proxy option. As you will read it has helped people alot.
You just might have to open ports with your ISP. Get sony on the phone and tell them your problem, and ask which ports could increase download speeds. Maybe check this out as well:
Good luck man!
**EDIT** I just read it could be a bandwidth issue. I have a 500gb bandwidth cap (and never exceed it) but yours might be different. Just something else to explore.