Pathetic service from CellC

I have been trying to get hold of Cell C Collections department for more than a work. I've been requesting a letter from them but no one is coming back to me. I called in several times. I get transfered from one department to the next but no one is assisting me with what I'm requesting. This is pathetic service. How can a department take so long to get back to someone. Staff don't know what they doing as no one can assist. I requested to speak to several messages but there's always an excuse. I was given a manager number Colleen but it says number don't exist. This is unacceptable from a service department. It's ridiculous to be running around for stuff but it's called a customer service department? I want a collections manager to call me to assist me with my query.