handed to collectors 10 months later after cont en

Hi my name is Mr S pillay . I am absolutely disgusted with cell c , clearlry an organisation to questin customer ethics. My contract ended with Cell c Nov 2014, I sent through all relevant docs to end the contr as requested and received confirmation of all docs received and the contract was terminated as per my request, no outstanding amounts. 10 months later I get an sms from a collector say I owe cell c an oust amount, furiated, I called cell c customer service/ legal ,asked them wats going on,we handed over u to collectors aug 2015, no correspondance etc to me the customer wat so ever for 10 months and jst handed me over, is this organinsation a joke or wat. Ask legal why this happen,they resp,I don't knw.I will b seeking legal advice as to my knwledge all amounts were paid in full and cell c hands me over 10 mnths with no correspondance to the customer me.during the contract term I received statem religiously via post, so wat happened to correspondance. Cell C disgusted,employ people who are capable cause they are clear not,perthetic.You cannot get a straight expl,all they say is I don't knw,fustrates u,want to *****