See, thats where your going wrong....
Your suppose to say
hang on tick, I'll just put you on hold and then carry on with what you were doing. Then look at your phone afterwards to see how long they held on for. I think the longest I've had HSBC on "hold" for was about 8 minutes. Fuck knows what he was saying but it sounded like he was getting blown at the time.
Have you signed up for this? It takes a while to kick in but it does work with nuisance sales calls, etc, etc.
http://www.tpsonline.org.uk/tps/what/