Worst Customer Serivce

I have been trying to cancel my wifi contract from 25 January with no luck. I emailed customer service to cancel my wifi with immediate effect, i received an email a few days later asking for some more details in order to help me. I sent them the details they requested. A few days later I received another email stating that customer service cannot help me. I need to either phone them or email some retention email address. I tried phoning 083 135 a few times can you cannot get an option to speak to a representative. I googled a few numbers, phoned them and got no response. I then emailed the retentions department for a cancellation but they also cannot help me and asked me for a phone number for them to phone me as they are not allowed to cancel a contract via email. I sent them my phone number on 27 Feb and have not received a phone call as yet. I have now cancelled my debit order and refuse to pay until this matter is resolved. They have the worst customer service I have ever experienced.