ive been double billed for 5 months for what was supposed to be a upgrade

In July 2018 phoned the business LTE call center to upgrade my 15GB LTE to UNCAPPED LTE, the person who assisted me went and added the uncapped as a new line to my account, so from august 2018 ive been double billed every month for 2 LTE packages, i have since then phoned the call center numerous times , every time they tell me the responsible person is unavailable, ive emailed the person responsible for the mistake, only to get no reply, eventually someone in the call center gave me the department supervisors email address, he also never responded to my query. Can someone please assist me to get the 15GB cancelled, and all the money ive been double billed for, i would like credited back into my account. i have also been struggling since November to get the adsl on my business line cancelled because to create a profile in order to cancel the adsl myself as i was instructed by the call center, it requires a business registration number, im a sole proprietor, so ive never had a registration number.... can someone please help me?