The IRS is seriously backlogged due to all the new tax laws and extra stimulus filings, as well as unprocessed 2019 returns left over from the COVID shutdown. Unfortunately, contacting the IRS will not speed things up. Lots of other folks are still waiting, so please continue to be patient. Also see:
Why Tax Refunds Are Taking Longer Than Usual (forbes.com)
The IRS is sending out Stimulus #3 payments in batches, and will take a few weeks to complete them all. This one comes to you separately (and automatically), not as part of your 2020 tax refund. You can check the status here:
Get My Payment | Internal Revenue Service (irs.gov)