Had a service recently. Ever since there is an annoying humming sound coming from the pump which is being amplified by the copper pipes in the system (diagnosed by the man). It is five years old and says no need to replace it if i can stand the hum! Gave me a quote if i want it done. Isolating the pump appears to be a relatively simple job. How much should it cost, labour + cost of pump? Dont know the size of the pump but we are have 12 rads + hw.
The cost of a CH pump obviously varies acording to size but Screwfix do them from about £90.00 up then of course the labour will depend on how easy it is to get at the pump but it is usually a fairly easy job, I don't know what labour charges are like in your area but it shouldn't cost too much,personally its the sort of job I'd do my self.
I had something similar after the last service. Turned out that the engineer had left the thermostat on the boiler up high. Turning it down to half cleared the problem. (took the gas fitters 3 visits to work it out)
Some pumps have a 3-speed selector. Turning the speed down may help. It's a matter of trial and error really, to see if the system still operates properly on a slower speed.
For a pump swap, there is an isolating valve on both sides of the pump, so a swap should take only a matter of minutes. Then there's the electrical connection. That should also be pretty quick.