Sorry I can't help you with your problem, but, just a word of warning re: the leaking oil. Heating oil has a marvellous propensity to penetrate the ground and home in on any sewer that happens to lie beneath. If flowing to a small, rural sewage works, even 20 or 30 litres getting into the works can severely impair the treatment process which in turn will lead to serious pollution of the receiving watercourse for several days until the process recovers.
I'm only telling you this because, as part of my job, I have been involved in a number of such pollution incidents, and it is not difficult for the water company to trace the heating oil back through the sewage system right to your door. Charges for the cleanup operation, including several days tankering of improperly treated sewage to another site for treatment can amount to tens of thousands of pounds. Add to this the possbility of a further bill from the Environment Agency for reinstatement of contaminated land, and it starts to become a very costly business (although SHOULD be covered by your buildings insurance).
Not trying to scare you, but just make sure your leak is properly contained before it does any real damage