Verizon sent me to collection

I had Verizon for years.  I closed the account on October, 29, 2019, because it was too much for me. At the time , I was a single mother with three children in college.  I had a final bill and asked them to give me time to pay. I paid the account on Dec 31, 2019. But, on January 18, 2020, was reported to the credit bureaus. Due to current economic situation after COVID, I have been forced to apply for loans to cover my mortgage, but my credit dropped so low because of Verizon reporting me, I can find a decent loan. How ironic, at my home, we still have Verizon services. I have reached out to Verizon so many times, but no one is able to help me.