would you bounce me out the door if you had previously been warned that the price may change by the callcentre cdepending on the job time?
Of course not, if someone is coming to quote me on a job then I can decide whether to go ahead with them after. I would never imagine any engineer arriving at a customers site to actually do a job for which a price hasn't been agreed.
IF I was advised of this by the company I would point out to them their own T&C's don't make this clear and that they are selling via misleading advertising.