Indeed £55 - just ask them http://www.dyson.co.uk/survey/default.asp?id=SERVICE_REQUESTI assume that this call out happens regardless and no-one else has such insurance?
I think it will replace it though if things go wrong.
IMHO Henry's are also good cleaners and if I was going to do the job the OP suggested I would probably hire the industrial jobs that my chimney sweeps use
(I'm stopping talking about hoovers now)