Afrihost promotion false advertising

I signed up for fibre in Nov 2018. They were offering free line installation, free modem etc. Vumatel came and installed the line and all was great until vumatel mails me 4 months later for payment of about R2,000 for the installation saying that afrihost haven't paid it, although vuma acknowledges the promo as per the mail I forwarded to them from afrihost. Afrihost and vuma are not honoring the deal.