It doesn't matter what your small ISP is doing now as prices will have to rise as input costs like electricity and gas have risen. Staff are demanding pay rises, too.
What they do next year is irrelevant in the terms of this argument, although if you do want to start on next year, VM are ALREADY baking a swingeing RPI plus 4% increase for next year, that'll be magnified for any customers on discounted deals. And whereas if my ISP increase bills I'll be able to take my business elsewhere without penalty or renegotiate, VM customers won't.
Coming back to the input costs, VM's latest results are due in three days but at the time of writing the most recent Q3 2022 results showed VM boasting about "accelerating profitability driven by price rises and synergies" - and that was before the current round of bank-account bleaching prices rises, and after last year's galloping energy prices set in, with EBITDA* for Q3 increasing by 8.6% year on year. Operating cash flow for Q3 increased by £67m year on year, whereas revenue went down by £10m, meaning that operating costs must have gone down by nearly £80m, yet you're telling me that VM are having to recover rising energy and staff costs? Don't make me laugh.
I might also comment that VM are using RPI as their baseline index, which is based on a household family budget, which includes food, domestic energy prices (ie including levies business energy customers don't pay), entertainment and telecoms (so a nice little feedback loop there), travel costs, clothing, personal care costs, alcohol & tobacco, holidays and hospitality spending, mortgage interest and rents, domestic appliances and technology, all weighted to an average household. That doesn't in any way reflect the structure of VM's costs. VM's biggest costs are interest on their enormous debt mountain, and that's mostly long term fixed rate debt.
So, if we come to the rub, why are you trying to rationalise VM's price increase, when the available facts don't indicate it to be fair or reasonable?
* For the uninitiated or disinterested, EBITDA = earnings before interest, tax, depreciation and amortisation, which can be considered the cash-equivalent profit from operational activities.