Refusal to provide me a closing balance

I canceled my telkom adsl line on the 14th March 2015 and was told at Promenade Mitchells Plain that they can only process the request Ref:A1 ***. Telkom was only suppose to bill me lawfully until the 14th April but delayed the process and canceled the line on the 29th April and billed me until the end May R750 odd for a r399 contract. 2 billing disputes logged one at the branch and several attempts of calling automated voice mails. Telkom refusing to provide me a closing balance. Both the branch and 10210 contact centre agents are telling me they cant provide me a closing balance and only there to process the cancelation request.