Please kindly urge Cell C to send me my paid up letter

Hello Peter I made a settlement in the contract I had with cell C and immediately ask for paid up letter since I was going to use it on something that was an emergency at that time. They said it's going to take 3 to 4 working days, I made a payment on the 13th of April but till today I did not receive my paid up letter I've been trying to get hold of them and keep on waiting me but nothing appears after the period they are promising. Please assist me with them sending me my paid up letter as quickly as they can cause I urgently in need of it.