Openweb wants me to pay for services I did not use

All was well with the internet and problems started when I requested cancellation. I sent an email through on the 7th of December 2018 requesting assistance with the cancellation, as I found a new deal with Telkom, which was set to commence 01 January 2018. I got a response on the same day directing me to their cancellation link of which I followed and filled all the required details. I thought all went well, but to my surprise a debit order of R139 went through on the 5th of January with the full amount and I reversed it and contacted them on the 8th of January to find out what happened to the cancellation. Their response was that they did not get the cancellation request and was given a cancellation format via email to fill in of which I did. Today on the 22nd of March 2018 I received an email from Credit Intel stating that their client Openweb handed over my account for collection of R368.84 with reference OPE001OW50816. My main concern is that I did all I can on my side to cancel and I feel they intentionally delayed it in order to milk extra cash from me and I refused. Another issue is that from the beginning of the year I was with Telkom, so what is that I charging me for as they never rendered any service to me? Please guys be very careful!!!