I have a 5G router i pay montly on debit order

I have a 5G router i pay montly on debit order. I left the country in April and i started to email the company requesting them to switch off so that i do not pay for service i am not using. Several emails i have written, they do not respond at all, instead they just give a reference number and say an agent will call me. I keep telling them i am out of the country. They are very uncooperative