have just had a good read through the small print, i see how they make their money - they hold the majority of balance back so at the end of 3 years you still owe alot, and have paid the 6.8%apr interest on it for the duration.
for me, financed sum is £27.6k. monthly payment for 3 years is £402, then there is a "final payment2 of £17.8k!!! so this back end loading they can make 6.8% on all the way through!

i will be following tims guidance in the opening post i think!