[OXO cube]

recently purchased a couple Scalextric C052 escorts 
these cars have both been painted , badly , with what looks like rattle can paint 
would like to try to restore them 
so 1st need to remove the paint 
tried this before , without success , the body turned into a squishy distorted mess

any tips / products to safely remove this paint without shrinking / distorting / ruining the body 

thanks in advance
kev