Overpricing and misleading adverti*****t

I bought an Explora (ID:***) on a Black Friday special which was going for R499 per month (compact) on price lock for 24 months. This included installation and all other related expenses. Installation was done on 14 December, debit order of R518 was deducted on 15 December 2020. I recently got an sms notification saying R898 is due on the 15 of January 2021. I called the call centre asking how come this has gone so up, no explanation was given to me instead I was sent from pillar to post.