Contract ended , cancellation sent no confirmation but still invoicing.

I have had an account for 24 months with Teljoy , I got unemployed but in February i settled the overdue of R4000.00 , I immediately emailed proof of payment with cancellation request as the 24 month elapsed.I sent 3 emails in 3 days confirming cancellation , no one rep****, Two days ago i get a call from a debt collector asking me for payments and I told him i paid up and cancelled but never received any cancellation confirmation from Teljoy.I am not sure why am I charged again monthly while i emailed and requested cancellation .And since I emailed the debt collector they never rep**** or acknowledged my emails they just buzzed me yesterday with the same number they used to call me 3 days ago.