If I read that right they took in a little over £100K and made a loss for the year of over £1.3M. They also had £2M less cash in hand at the end of 2016 as they did in 2015. You might want to dig a little in to their history on companies house as that to me doesn't suggest a company that is going to be around for much longer.
£50 for res but £300 for biz!? I bet they don't have many if any business customers with those figures.
Maybe the business option is an uncontended product (ie more like a lease line)? Interestingly if I click on "Buy now" on the £300 business option it takes me to a form to fill in but it only seems to have the residential packages listed.
Looking at the links, supplied earlier in the forum. This company works with councils to supply fibre to residential properties.
As for finance. It has recently received £11 million funding to enable expansion.
Appears to be a Hyperoptic type model.