More than 75,000 consumers have got in touch with Ofcom following a call from campaign group Fix Britain's Internet.
The organisation - an industry coalition consisting of Sky, TalkTalk, Vodafone and the Federation of Communication Services - last month began urging internet users who are unhappy with the service they receive to air their views to the watchdog in its consultation on the proposed reforms to Openreach.
Ofcom has ordered BT to give more independence and investment powers to Openreach, with the broadband subsidiary being run as a distinct and legally separate company with its own board.
The watchdog is hopeful its proposals will provide Openreach with the greatest possible degree of independence without separating the companies entirely, and lead to decisions being taken for the good of its customers and the wider telecoms industry.
Fix Britain's Internet believes the response to its calls to contact Ofcom demonstrate the level of public feeling about the standard of Britain's broadband infrastructure.
TalkTalk, Sky and Vodafone have been among the biggest proponents of a legal separation of Openreach from BT, as they argue this would improve the quality of service for customers, drive innovation and make the organisation more transparent.
Speaking to the Daily Mail, TalkTalk Chief Executive Dido Harding said: "What is it doing with the profit it makes from Openreach? Without separate accounts you cannot tell where the money is going. So, no, I don’t believe it when it says it’s not being spent on sports rights.
BT has responded by insisting it will provide ultrafast broadband speeds of more than 100Mbps to 12 million homes by 2020.
However, Ms Harding pointed out that Openreach's ultrafast broadband is "mostly fibre with a bit of copper cable on the end", which makes it slower than "proper fibre to premises" technology.
She went on to point out that while superfast broadband might be available in many parts of the country, lots of people still find it prohibitively expensive.
As a result, she believes a standalone Openreach would have a greater incentive to make its product more affordable.
"We would have a business whose sole purpose would be to provide national infrastructure that serves all customers equally," Ms Harding said.
"As a FTSE 100 company it would be good for pensioners, too, because it would be so stable. Would it be good for BT? Well, if it were whiter than white, then separation should not be an issue for it."
Last week, BT hit back at the criticisms being made by Fix Britain's Internet by publishing a joint advertisement with Virgin Media in national newspapers.
The ad stressed that £15 billion has been invested in broadband technology over the last five years and that Britain boasts faster average download speeds than France, Germany, Spain and Italy.