INVOICE FOR A CANCELED CONTRACT

I officially canceled my Wi-Fi contract on the 1st of July 2024.However MTN kept taking me from pillar to post until they decided to cancel my contract only yesterday 15th July 2024 and now today they sent me an invoice for R656.52...For what as the have already debited me for month of July...I refuse to pay for services I didn't use...Also at has been 24months of buffering and no network. That's why I moved on to a more reliable service provider.