Error message for past 2 days when i go to CHANGE MY PLAN page

I need to change my plan, compare plans and then select, but i can never get to this screen because when i click the LINK it says ERROR for past 2 days. I noticed this forum had the same issue posted in 2018 and they had to PM the person. I have been on the HELP line and they told me to go to the CHANGE MY PLAN page, but still get ERROR. please advise, many thanks, LB