I"ll bet coffee that you probably had accrued late charges, and they assessed interest on those late charges. If you do not pay those late charges and interest they will keep your title until you pay.
Perhaps they added insurance to your loan because they were under the assumption that your insurance was cancelled by your insurance carrier. If this is the case, then they probably notified you that there was a period of time in which you did not carry insurance on the automobile, and they increased your payments. Perhaps you ignored the letters because you had insurance, and kept on paying the original amount. Now they want the money they paid for insurance, and will keep your title until you pay. If this is the case you need to contact the finance company and get them to give you the dates where they showed you no insurance. You will need some type of paperwork from the insurance company of record during that period showing you had insurance.
Now, when you say "After making the final payment ahead of schedule". What do you mean by that "Final Payment". was that one payment, or what you thought was a payoff amount?