@cjd may be able to offer some explanation.
Happy to share a business lesson
We introduced the PA service as an adjunct to our normal customer service operations - for which we won the Institute of Customer Service Award btw. We did it at marginal cost to us as we could soak up the extra PA calls across our 20 or so tech support staff. We have charged £1 per call (regardless of call duration) for 10 or so years with no minimum charge and no minimum use per month.
The service has grown and there are now dedicated staff answering those calls. I recently got round to reviewing our costs because I was being asked for more staff to meet growing demand and found that we were we losing money on the service - on our staffing costs alone. So we make a loss at the gross margin level before any other charges like supervision, network cost, call costs, overhead etc etc. If we added another member of staff to cope with the extra calls we'd lose even more.
So we did a business case for continuing the service or shutting it down. We also did a competitive review and found that no-one of any size was as offering a service as ad-hoc and cheap. Almost all have minimum monthly plans with no pay per use options. All were far more expensive. If you do the sums yourself, it's plain that it can't work - work out the minutes in the day and divide them into wages, NI and pension cost (we're a living wage employer). There are hidden charges in other services too, like telephone numbers, call back charges and call forwarding charges. And probably all manner of worker exploitation scams. All of which don't apply to us.
So we decided that we could keep the service, price it competitively and make a small profit on staff costs. We increased the price to £2.50 per call which is totally pay as you go - some people are making less than a call per month, they can still do that. We then have a series of plans offering discounts - they start very low, £10 per month for 5 calls (so £2.00 per call) going down to £1.50 per call for heavier users.
It will be possible to find cheaper services I'm sure, but please bear in mind that anything much cheaper is not sustainable, unlikely to be as good and most will contain a catch of some kind.
