Netstart ****?

I cancelled my Netstar thing last year in April and made my last payment then. I have confirmation from my insurance broker that the said contract had been ended. Now, months later I get told by sms that if I don't pay you immediately that you will be handing me over to lawyers. I tried calling you to sort our but am told I have to either download your App, which I won't or WhatsApp you help Bot. Doesn't work either because when you choose option number 7, which is Netstar contact details the Bot does not respond. What a terrible way to deal with former, and m potential future clients. No proper chain of communication at all and you other options don't work. Right now I feel that this is a bit of a **** from Netstar?