Device defective ... how it went ....?

It is difficult for some to decide which is (in my time) were no customers recessions. Most write that it is a good thing, but the event of damage has not yet occurred. What about it helpful and why I forgive then 5 stars?
Each must be clear that the first two years automatically lt. Law to be covered and the 100%. The insurance does not occur until the expiry of the statutory warranty period. And here lies the subtle difference of graduation (in the 3rd year 80%, 4th year 60%, 5th year 40%)
That's why I describe my case here. (Correspondence exists)

Bought home theater system in the year 2011 for 07- 131 .-- with extension warranty for 4 years for 13,99

In 12-2013 playing the DVD does not work anymore. The device is not economically viable, that is it will be paid.
Residual payout (ie 5 months after the statutory warranty period) is 69.72 when I go to reclaim the device again (10% min. 40 .--) deducted
Remains a residue of 29.72. I prefer even now the sum insured from 13.99, I have actually 15.73 again covers the 100% to give me a device to buy, five months after the statutory warranty period.

That means: I pay 114.27 from his own pocket for a new unit for 131 .-- !!

To this day I do not understand why I only get 70% of the purchase price as set out in the contract documents instead of 80%.
Unclear to me was the fact that the residual value is calculated only on the net amount.
Only after a long correspondence we have found a better solution.