Any advice will be welcomed
More information would be welcomed.
What car do you have? Your profile says it's a 1.4 si, which is not a MK3. You might get a more knowledgeable response over on part of the forum more appropriate to your car.
Has it always been poor or has it started recently? Are you using the OEM radio and antenna, or has something been replaced or disconnected recently?
Are you talking about DAB, FM, AM, or maybe radio over the internet?
Personally, I use DAB all the time (MK3 car) and have never experienced any problems with reception, except in locations where I would expect it (eg deep valleys in remote parts of the countryside). Of course, the different units fitted in the different generations of Jazz may behave differently.