Buy a new tank?

Can you post this in the Help & mod zone please, thats what its there for....

hiya this problem ive been havin is wuite frequent now and this wat it entails when i fill the car full or near full of petrol i have problems. these include an awful smell of petrol, drips of petrol under the car and also petrol on bottom of tank etc..

now me and my dad investigated into this and we lifted the back seats and looked arond the top of tank there etc..there was petrol lyin around there and then took the top and replaced the rubber seal and made sure this was all tight and fitting ok and then dryed petrol around off and took car for a run and looked again and petrol was around the top again... so we made sure seal and everything was in order and it seems to be so whY is the petrol leaking out through the top here etc.

please help as petrol leaking number one is dangerous and not good.. i dont know wat to do only way around this is not to put much petrol into it but next buyer will not know this

thanks