Problem is that 'Public Sector' covers too many strands for this type of proposal to be realistic. On one hand you have front line staff who are underpaid and very stressed, and where job vacancies cannot be filled because it is just not worth it. On the other hand you have shocking inefficiencies (I have private sector friends who have worked at various points in time in 'admin-type' areas of the public sector - they have all been rendered near speechless at the low levels of productivity); You don't solve either of these issues with a pay freeze, all you are doing is a spot of marketing ahead of the election.
The difficulty is that what is really needed is a roots-and-branch reform to remove inefficiencies, reallocate resources to the areas that are stretched, and lea dto long term savings. This is usually possible even in huge organisations (we have seen it happen to the privatised industries, for example). But that is near impossible in public sector because (1) Unionisation in the UK, (2) the short-termism of UK politics, (3) you need a strategy to deal with the fall-out (you need to be dynamic enough to deal with effect on unemployment etc, and regional imbalances that would arise), and (4) The initial investment would be huge (eg you can only cut costs in HMRC for example if you first simplify the tax laws in the country).
There is one EU country that I think has started such a reform but can't remember which one, and it has only been recently so effects not yet known. In an economy of our size it is theoretically possible, but would be political suicide and might create too much of an imbalance of borrowings in the short term to be sustainable in terms of our global position as a country.
So the govt avoids the big problems and announces a few crowd-pleasers that will probably cost more in red tape to implement than is saved, and also will, in some cases, be illegal (wage cuts, for example). And I guess all the parties equally hope that global hyper inflation will come along at some point to clear up the debt mess, so we will end up with the 70's again. Which will be a tragedy, however often it gets repeated.
Sigh