Our accountant is raising their fees based on our revenue figures. They have a broad pricing model based on annual revenue, that doesn't take into consideration any other factor (e.g. number of transactions, complexity..etc). Our revenue figures increased during the year and hence they are revising the contract so we'd pay three times as much as what we paid at the beginning of the year. We are looking for quotations from other accounting firms, but we're faced with the question: what's a good price? Since accountants charge monthly here in Ireland, and we barely interact monthly (we do our own book keeping), it's hard for us to evaluate their worth based on the amount of work done since most of it will be done at the end of the year.
In ideal scenarios, there is no reason to increase the price based on the revenue unless working involves increased efforts to a substantial extent. I would quantify the efforts required in hours and get a quote from the freelance consulting accountant. Based on your details, it appears that you do most of the bookkeeping activities and so the consultant has to validate and do Govt formalities. Unless you are doing some specialized business where you will need to defend or work with Govt officials for certain things within accounts, you should be paying charges wrt to the effort involved and yearly inflation rise.