Of course they will charge them for the capacity

I think you meant over-charge.
It depends on how savvy MWEB's procurement team is in knowing industry standard prices. My bet is they know what they're doing so they're getting the price everyone else would be getting. Telkom would really be immature to charge them a higher price just because of a grudge. This will be anti-competitive and they could pay a fine for it if proven in court (something Telkom has had to pay in the past too)
With all the corruption within Telkom being exposed (I guess the employees have started to whistle blow despite constant threats of them losing their jobs if they said anything) I don't think they'll handle another "scandal" like this very well.