Cell C contract after 10 years

Ive been struggling with Cell C for a while know. Ive got an contract with them for almost 3years but which arent on my name but my brothers weve been struggling to put this contract to new ownership and weve tried a few branches to assist us everytime they just say theres something on my name or that I dont qualify. I mean none of these assistants could tell me what it was. 2 Weeks ago I went back to N1 City branch to check again same response so consultant told me she needs to phone legal to take it off wotever it is will contact legal and come back to me.A week went by didnt hear anything from Cell C and almost another week nothing so I went back into the N1 City branch to find out wots happening.Answer was she couldnt get through to them really for almost 2 weeks? Then she phoned while I was sitting there after 45min she got through to legal to find out that I owe them R675 for a contract i had with them 10 years ago and which ive finish with them omw.Why didnt anyone contact me in the 10 years about this my details havent change. Why couldnt they send me a letter to tell me about this the phone was delivered to my house im still living at the same adress why wasnt there any contact made through post or something. They so quick to get your number to tell a person about specials and contracts why coulndt they do the same I mean 10 years.