WHoo hoo....we found the problem....or at least a part of it.
My dad and I took out the backseat last night when we got home after work because he kept saying that he thinks the petrol pump is not getting power.So we took a look,he found the wire that supplies power to the pump,tested it and found that there was no power coming to the pump.
He then cut the wire and then gave it power from the main power line (was a thick red cable which was also found under the back seat) and voila.....the car started immediately.....even started much easier than it normaly would.
So yeah...my dad finaly found the problem and this weekend we will trace the wire and find where the problem is and replace whatever needs.
Guys thanks for all the help,especialy to Big Evil for all the quick and very helpfull advise which pointed us into the right direction from the start.