When there’s no market pressure in a sector, why would any company do anything but the cheapest possible customer service offerings? I recently had to deal with

When there’s no market pressure in a sector, why would any company do anything but the cheapest possible customer service offerings? I recently had to deal with trying to convince my ISP to cancel a charge for a wifi router that I don’t even have, and upon them crediting me for the over billing, I received an email from UPS telling me a router had shipped (which I will have to send back). This all increases revenue for the company and it’s not like there are other people who have a fiber line to my house, so what am I to do?