bad service

had an MTN contract sim that never even worked , once im in arrears i paid it up and requested a paid up letter , just after that i had a default under my name , i called them several times up until i got hold of one rude consultant who told me they cant assist me as it reflects on their side that the account is closed , all i needed was a paid up letter so i can fix my credit record , till today nothing , im so disappointing in their service , they treat people like ........