Sorry to hear about your troubles with your Hotpoint Hal2000, mine was the Dual Clean model but I mostly used it bagged because of the mess involved with the dust container. Apart from cleaning everything thoroughly there isn't really much else that will help.
I also found Hotpoint's UK service useless, I was kept on hold for ages until I managed to speak to someone & they never reply to emails.
I haven't used my cleaner in months, but when I do I prefer it bagged because it's easier that way as you don't have to empty the container, wash filters etc. That's why I went for the dual model.
Also, are these cleaners still on sale with the EU legislation in place?