Paid up letter request

I really do not understand what cell c wants from me, They told me that I was owing them R70.00 rands which i paid last week and e-mailed the the proof of payment last week, i have been trying to get a paid up letter from them since then with no luck.<br> <br> Do they EVER do anything right??<br> <br> I am so tired of this network, I want my paid up letter PLEASE!