I filed my amended return and it was accepted. I waited the 20 weeks and when I check the IRS website it tells me to call them. I keep calling them with no answer

Amended returns are taking much longer than the posted 16 to 20 weeks ( 6 months to a year is the current norm)   and if the IRS wants something from you they will mail you a notice.  Trying to get thru to the IRS by phone is almost impossible ... they are only answering about 7% of the calls coming in and then getting a correct answer can be even slimmer so don't waste your time.