Internet and Cable is Bundled and cannot split out the cost -- How can I expense my internet for my home office expenses?

I have the same situation with the same provider. 

I made a good faith effort to allocate the cost to each service. 

I called the provider and asked how much each service would be if purchased separately. I added those two costs and figured out what percentage (of the "total") was cable and what percentage (of the "total") was internet. I then applied those percentages to the actual total bill I was paying for the bundle.

can you share what percentages you came up with? I know each persons situation will be different but just to get an idea? 

I like the splitting based on the un-bundled price, but how are you going to figure out, support, and document the work portion of the Internet vs. the personal use portion (web surfing, shopping, streaming)?