Worst customer service!!!

Hi I'd like to complain about Rain. I received a message that I'm being handed over for debt collection. I stopped using their WiFi more than 6months ago and the consultant I spoke to told me it's a Pay-as-you-use. They've never communicated with me about missed payments or anything. When I try to contact them for cancellation there's no response, even on requests for a call back; only emails and sms with reference no. It's been 2 weeks now trying to reach them with no luck😡