What do we do if they said they had no record of a DUI for him and of course he has no case number to go by but has court hearing scheduled?

My son 25 year old son received a DUI recently. He was actually driving another person home who was really drunk because it had been a few hours since he had a beer and felt totally sober. He got pulled over and blew a .07. The policeman asked him to blow again. He didn't want to but the policeman told him it would be worst for him if he didn't. This time he blew a .08. In talking with the policeman, he explained that he had had a DUI in the past and actually had been pretty much sober for the last 5 years, which is true. Since his last DUI was before he was actually 21. It had taken him all this time to work his way out of it (classes, fees, jail time (15 days) and 5 year probation. The policeman told him when he got to the station that if he blew again twice and blew .07 again he would remove the handcuff and let him go. Again a .07 the first time and a .08 the second. The policeman actually removed the handcuff and shook his hand and thanked him for being so polite and cooperative. He spent the night totally sober in jail and posted bail. When receiving his paperwork the next morning, he noticed there was no case number. He obtained an attorney for guidance and was told his DMV hearing was today. He called yesterday to say he had never received any paperwork. What’s going on here?? Could the policeman have had a change of heart and not filed the paper work?