Ssd and Associates I want my paid up letter and clean my name

They have been calling me to pay my MTN account, Payed my MTN 30th May 2022 in full till today haven't received my paid up letter, instead another company is calling me to pay money that I've paid long time ago, saying that I still owe MTN yet when I'm calling SSd & Associates it's stories that MTN will give me paid up letter and clear my name. When going to MTN they say it's not true they Ssd associates is the one who has to clear my name.