hi i have a panasonic head unit thats served me well, but it's randomly pausing for ages when playing discs and the radio reception has deteriorated. i have a £100 budget for a good head to replace, must play MP3 discs but a usb slot would be a bonus to. what are good brands and units to go for? i have a mondeo so would assume that i can easily pull one out and put one in. i'm no expert!