I wont pay for a service that i never used.

I had a contract with telkom for R99 per month for data on my modem, when the time for my contract to end was nearly due, i was contacted by a call-centre agent to offer me a R200 package for a router and a new sim, i took the offer... when the new debit order was captured on their system, they tried to debit R1800 which was not what we had agreed upon... i had called them on many occasions and no one was able to assist me.... eventually they contacted me and i explained the whole situation to them and i was advised to complete a cancellation of sevices form of which i did on 3 occasions and they kept on saying they have not received it... on the cancellation form i had stated that the router is still in my possession and was never used ... i still have the whole package including the sim card... i requested them to check if the sim card had shown any activity of which they failed to do and get back to me... all the agents i spoke to had said they would give me a response as soon as they had solved the matter which they never did. This query is as old as 2016. Now they handed my case over to nudebt of which they also haven't been able to assist me... The package still has never been collected from me and they still keep telling me i owe R3550. I refuse to pay for a service that i never ever used. Please assist in this regard and if they are unable to assist me please may i be refferred to a company that deals with such queries.