Do you know the person whose file you wish to download ? If so, can they split the file into two using software whereby you can use the same software to recreate the original file after downloading ?
I've limited knowledge of downloading but suspect to restart a download part way through it may need to be set up at the originating end. Since that's not an option I suspect you'll need to get a greater download capacity from somewhere.
Have you tried looking at download managers? I am no specialist, but there are free ones available and some claim to support pausing and restarting downloads.
Sorry, we can't find any related questions. Try using the search bar at the top of the page to search for some keywords, or choose a topic and submit your own question.