What is taking so long to fix, surely Windows Update uses a specific protocol etc and you just unblock it, really this is not acceptable. Your network configuration people really need to get advise from other ISP's as your network is continually having issues, every few months there is something only Afrihost suffers from.
I don't think it's a case of being blocked/ unblocked. Something happened with them where they aren't performing well on our network. From the testing we've run, it does seem intermittent - we have a team looking at this daily.