WRONG BILLING/UNPROFESSIONAL UNHELPFULL STAFF

this is my 4th upgrade with 8ta. I was overcharged in Dec 2015 billed for stuff not in my contract which was queried on the first week in Dec 2015 my account was not rectified but debited. I upgraded on 8 December 2015 & received a bill in Jan 2016 for R1123 which they say was prorated. Since I received my bill no one in the call centre can help me, they say there are no records of my upgrade but I do not understand how I am billed for the upgrade. I am sitting here with a Sony M4 Acqua which I cannot use & i am been billed for. I am now very frustrated coz 8ta has a bunch of idiots working there who do not know the products. I am thinking of cancelling my contract with 8ta after being a loyal customer & receiving such service. I am also thinking of getting my attorney's to sue 8ta for breach of contract as I am totally appalled with the service received thus far.