"The Incorruptables" Mexican cinema Question

Does anyone 'round here remember a Mexican film from the mid- to late 1980s about a young child who died, but whose body did not decay? The father took his son’s “incorruptable” body to the Vatican to have the miracle verified, but there encounters a “corrupted” bureaucracy plagued by bribery, inertia, and disbelief. The father finally leaves the Vatican, and the son comes back to life at the sound of the bells of an ice-cream truck. (I may be fuzzy about the closing details – hey, it was 20 years ago!!)

Is this familiar to anyone? What’s its title? Who wrote the screenplay? Was it an adaptation of a novel? Is the film on video or DVD?

Thanks for your help!