Bad customer service No refund processed

I signed up for tracking device in 2022, we agreed on the amount to be paid but when an invoice came, it was different amount. I have been contacting Netstar and they listened to the call record but still today, I don't have my refund. I spoke to Eunice in 2023 September and she acknowledged. Also took over tracking device from pre installed devices from Nissan. Before taking the tracking device we agreed that I will pay the amount as agreed with agent other call pertaining to a new device I wanted. They agreed but after activation I kept paying the original amount that Nissan was paying. I have reference number to this effect but no one from Netstar is willing to pay back my money.