Telkom overcharging me and they dont care

In May of 2019 I upgraded my data contract with Mondo ( who is a trade partner of Telkom). I signed up for a R139 pm for 10 gigs of data ....... this never happened.Since upgrading my contract in May I have been charged R499 every month since, regardless of the slew of reports, escalations and reference numbers regarding them over billing me.I am at the end of my rope and have no idea what else to do but keep reporting and praying that one day someone at Telkom will take pity on me. Ref numbers ***a, ***a, ***a, ***a, ***a, ***a,***a, ***a,***4, ***8, ***6, ***9.......................seriously !!!!!!!!!!