OS Catalina Upgrade Failures

Hi I have a13 inch Macbook Pro purchased late 2015, 2.7 core i5 8gb ram. I finally got an invite to upgrade my OS from Mojave to Catalina (after 6 months) over a month ago but each time I try, my OS update download times out after 511 mb of the required 8gb download. This happens when I attempt downloading from The Apple Store too. What is the best approach to solve this problem so I may upgrade my OS? I am trying to avoid calling Apple direct. This is really frustrating, even my windows OS surprisingly upgrades better. Thanks for your help.

Thomas