I switched from Spectrum Mobile to Verizon. I waited for 5 days for Spectrum to unlock my cell (Galaxy S21 Ultra). I called every day and Spectrum kept pushing out the day I'd receive the unlock code.
Then I came across CellUnlocker.net. Read some reviews and figured it was worth a shot. They emailed me the unlock code within 2 hours after ordering.
Would use them again and highly recommend!