How can they issue a free service package 9 months before I bought the car? Are they right?

Easy, like the warranty any service plan will start from the date of first registration unless its an aftermarket product you buy later. But you did not buy the plan, it was free, thus would start when the car was registered.

The fact that your car was not serviced until it was 19 months old would probably mean that the warranty was null and void if you had required work doing.

Another example, the wifes car is a year old next May. We have 12 months to buy the manufacturers 2 year service plan, we will get it sorted in April. The car will gets a service the following month and the 2nd 12 months later. Essentially the start date of the plan will be 11 months before we buy it but its clear enough in the T & C's.

We are buying it late for one simple reason, the money is better in our bank than the manufacturers.