I'm confused. The camera in total is £530, add on a £25 charge, i'll pay £555 off in September. I'll have that money in september so I'll pay the whole £555 in one big go and then it's sorted and fully done. I don't have to pay any interest or any of this monthly stuff or use a credit card because it'll be done within the 6 months. Where is all this other stuff coming from like pay with a card or i'll get 27% interest or something... because it's confusing me even more...?
Your £25 charge is the interest. Credit card with 0% for 'x' months doesn't have such a charge.

You know I'm certainly not a 'banking basher' but the banking sectors involvement in house prices is simple economics.