Change Plan Doesn't work

I have been trying to change my plan (my monthly bill continues to increase) online on and off for months and the system is permanently broken and just says "sorry please contact one of our representatives for help" the call tree is nearly impossible to get a hold of a live person to get this taken care of. Is there another solution? Seems insanely misleading to even pretend I can change my plan online when the website hasn't been working for months on end - and based on other posts years.