Its a ballache being charged by insurance companies for advising changes HOWEVER as said above you could stand to lose a whole lot more if you dont.
When you read their policy docs they always state that you must notify them of ANY CHANGES to the circumstances declared at time of taking out cover.
For the same reasons always fill in the V5C (reg document) change of ownership at time of sale & send off to DVLA straight away(keeping a copy if like me you dont trust them!)
Dont give the insurance pirates any opportunity to say you havent complied with the terms of their contract.