Horrible connectivity negatively impacting business

Daily Internet Outages for my business is not acceptable. We own a children's learning center. From 3pm on each day, parents entrust their children to us for tutoring - for a month, we have had nothing but trouble with our internet connection.  Our phones are tied to the internet, so parents cannot contact us, not to mention new prospects.  This has been going on for a month. I am told it has to do with their outside signal.  Either fix it immediately, or do not sell a service you cannot stand behind.  Someone must fix this issue. You courted us to get our business and now we have to put up with this?  It gets real simple for me at this point: it is either permanently fixed by Thursday December 8th or we will move on to a competitor's platform.