It sounds to me like your ISP is blocking your use of aMule.
For what it's worth, I'm Low-ID all the time. There's no solution for me because of the nature of the network I'm attached to. But take note: this does not prevent me from getting downloads successfully! People attach way too much significance to High-ID vs. Low-ID. aMule is designed to work with either. High-ID only means that you will be able to exchange data with more clients. If you have adequate numbers of sources for your files when you're Low-ID, then being High-ID won't help much.
That's why I think your problem is more severe than simply getting Low-ID. If it was just Low-ID, your downloads would still work but would perhaps take a bit longer to complete. That's not what you're experiencing. You're experiencing a near total failure to download. That's why I guess it's your ISP.