Hi, I have an Ideal Isar HE24 Combi Boiler and it has started to make a lot?

Hi, I have an Ideal Isar HE24 Combi Boiler and it has started to make a lot of noise. Loud banging and loud clicking noises are coming from the boiler. It sound as though something is trying to click itself on. It still works, the radiators come on with plenty of heat and I get hot weater although the hot water has been playing up and I havent had guaranteed hot water when I need it.
i would be grateful for any help or advice.
Kind regards
Ray Sutton