Kia C'eed 2009

Hi, can anyone  out there who has a Kia C'eed give me some information please. My OH has one and is having Radio interference on the  car radio when using AM  radio  on radio 5 only when the engine is running. When the engine is switched off he receives  acceptable reception but when running it sounds crackly and  sounds like cars did years ago when they needed a suppressor fitted.Kia garage have consulted their Head Office who have confirmed that AM is weak on that  model of Kia.Has anyone else had the same problem or are we being "fobbed off".The radio gives perfect reception on FM. We are aware that AM radio is being phased out but we wanted to know if any other Kia C'eed owners were having the same problem.