i want to upgrade my Internet, but nothing else

just as the title says. when i go to change my plan, i select a new internet package. but when i go to hit next, it tells me i have to change A L L ALL of my other services as well. i do not need to change any other plan details. but the site and the app both dont allow me to proceed. no phone # to call, and im not making an appointment at a store. i should not need to do anything but select package > checkout. should be very straightforward.