Sour Rain services

Rain is probably the worst service provider I've had to deal with over many years. They acknowledge online requests with a reference number but that is where it ends. I've requested cancellation of my contract for many years without reaction from their side. They keep on claiming that I owe money on an invoice dated March 2020, but cannot provide the invoice. This invoice is conveniently also not available on my online account profile. I haven't used their services for the last four years. One is unable to get in contact with the right person to assist. Emails to them are either blocked or *** is apparently an unattended mailbox. These guys are utterly useless.