I'm in the sh*t

Back in the days when I had a Td Omega, I used to run it on a mixture of refined chip fat and diesel during the summer with great results

Right the problem is ........... Sat on top of my shed roof was 3 x 20 ltr plastic containers full of the stufff which I never got round to getting rid of

Sometime in the last week ( while I was on holiday ), some little tw*t has been playing with his air rifle and shot the containers full of holes

Now I have around 60 ltrs of chip fat that has been washed by the rain, down the drain pipe and into the drain at the back of the house

It has not reached the main part of the drainage system yet because all the sinks in the house drain away without a problem.
But at the shed end of the system, it is completly blocked up to the point that the fat has totally bunged up the sink next to the drain pipe

Ive had my hand in there and been scooping as much fat out as possible but I need to clear the rest of it out before it bungs up the rest of the system or the council and neighbours will be ripping my gonads off

Anybody out in OOF land do this for a living ?
Ideas please