Liquid Capital service plan is a **** - avoid!

I was contacted 2 plus years ago and sold this product: Pay for the next 3 years service costs over 30 months - avoid price increases and effectively have a constant amount paid every month instead of one off large payments. Seemed like a good idea. I asked KIA the cost of the next 3 years services and the amount was exactly the same amount that I would be paying for but spread over 30 months. Every year I service my car annually as I am always under the mileage intervals. In 2017 (22 November) I serviced my car 1 month earlier as I was going on a long trip. In my mind I needed to service the car in Dec 2018 again or earlier if I reached 15000 km. It slipped my mind and I called KIA during December and was told they are fully booked until mid January 2019. Liquid Capital will not pay for my service, which I have prepaid to them, because I missed the annual service deadline. Oh they give you 30 days grace but sorry for you if that falls over a busy time of the year and you cannot get your car serviced even if you tried. My view - I have paid for the service - whether I then get the car serviced a few months or km's this side or that should not matter. It is not a maintenance plan where there may be additional wear and tear costs, this plan will pay only for the prescribed book service.