Appalling Service

I tested my device in October 2023 and found it was not giving feedback and I logged a service call with Netstar and I got reference. I was advised I would get a call back an after a few days no call I made contact again and this time to cancel. I got another reference and a promise to call back which I never did. In November when I got the debit order I then reversed it together with the October one as essentially I was not Serviced for both months. I received a call from their collections agent on 8th December and I refered them to their reference numbers from 13th and 19th October and advised I will not be making any payments for services I didn't receive and that I have further cancelled my contract. I tried to contact Netstar via their chat bot but my cellphone number was not linked and I emailed their customer service and didn't get a call back or a response. I again reversed the December Debit order and this morning received an sms threatening me with legal action with costs.