I'm not going to defend every wage, but you're talking about organisations that are spending hundreds of millions of pounds a year. Manchester City Council's budget this year is over £800m.
They've had to make funding cuts of nearly half a billion since the Tories started cutting Council funds in 2010, so even if we're looking at £2m a year on senior management it's not the reason why the roads are full of pot holes.
The reason is simple. Many of the councils in Manchester have around 20% less funding that they did in 2010, but they still have mostly the same legal responsibilities. Nearly the entire budget has to go on schools, adult care services, and children's services. Once you add in other things that have to be provided like bin collections, you end up with almost no money left over, so the cuts to everything else are way in excess of 20%.
So, I'd suggest that pot holes are very much more likely to be caused by a lack of funding, than the pay of a few senior Council employees.