VOX Collection Dispute

I cancelled my contract with VOX in January with services stopped in March. The issue came in with collection, I told them I will be moving to Cape Town, so collection has to be in CPT. We received an sms for collection in April but no one pitched. Today I received an R2k invoice that my account will be deducted cause the collection “failed”. After sending an email complaining customer services called me, the lady claimed that I have to drop the router now or else I will get charged and she **** that a failed sms was sent. Which it wasn’t after checking our messages and a 3rd operator confirming this. I was willing to drop it off but after finding that the first operator **** and I have to spend my time during work hours and travel 50km I am not willing to do this as they are taking advantage as they are a big cooperation. How do service providers get away with this and to send me an invoice 6-7 months later is unacceptable accompanies with a whole string of lies that some tried to come collect, they called and failed to collect and I get billed or told to drop it afterwards to clean their mess.