Think someone sent them new batteries for their calculators.
doubt the problem has anything to do with calculators and batteries
its the methodology that causes the problems. Effectively the MNOs are saying the same thing as Telkom does when it speaks of a Line Access Deficit: the monthly subscription charge on a particular subscription service is set not according to the overhead cost of that subscription service but rather at a pricing that invites revenue from the voice minutes and data [etc ...] but the "Gillette priced" subscription fee is mismatched [revenue was over-estimated or has declined etc ...](in Telkom's case the overhead cost is the cost of maintaining an extensive copper network).
RIA simply applied the standard narrative as to the MNOs "profiting" from subscription fees on contracts rather than that the subscription fees are an important annuity type revenue that really does form a backdrop for how MNOs plan and construct their networks. Once you move away from that narrative you see that the need to increase this sort of core revenue is pivotal to operators expanding their networks. Change the methodology and you get to their conclusion which from a NETWORK OPERATOR point of view is 100% correct. From a service providing point of view the story is a little more complicated - especially if their is legality, regulatory and PR (backlash) issues to consider.
The situation is strained for the operators - CTR adjustments and the decline of demand on voice ... - and the ability to generate the sort of big revenue from data that justifies the sort of scale of investment that mobile operators have to make to keep their smartphone orientated networks a worthwhile investment.
The very basic bottom line is that if you are paying the same or less each month to your (not so) trusty MNO chances are that they have less money to invest in the network. There is a real need for MNOs to drive up the ARPU across segments (artificially dividing the market into segments and having an ARPU per segment) and unfortunately as much as data is a driver the simple reality is that operators have to invest fast and hard (and the little spectrum snafu isn't helping).
However none of this addresses the more pertinent legal and ethical issues of increasing a subscription fee which is locked to a contract and is advertised in all of the marketing material as the base price. Ultimately while it may be necessary to adjust prices of subscriptions this justification does not extend to unilaterally increasing a subscription fee that is locked into a contract is the issue - if there is a prospect that such a change could happen it should be a lot more explicit than any contract from an SP in SA that I've read and it should either have the same safe guards as tariff increases (ICASA oversight) or have a fixed ceiling (the SP may increase the subscription fee by an amount not exceeding CPI + 2% pa)
The situation - IMHO - is worse for Vodacom than the other operators because of the particulars of the contract drafted by Vodacom - although Vodacom's regulatory departments know my view on this

Of course if my view on the NCA (atrocious piece of legislation that it is) is correct then the first operator to jump onto the wagon gets to hit the others with a stick and avoid loosing a lot of money ... (the last thing an SP wants is to have the decision to increase fees set aside by a court affecting both old contract subscribers and new ones ...
/abstains from injecting a metaphor of Vodacom taking batteries out of calculators and into more phallic objects into the discussion