oil central heating system?

the little black pump on the front of my system was dripping oil i called out a man to fix it. 40 minutes later he says it done. that evening i turned it on but it was still dripping and there was two screws on the floor ? 10 minute later the system was making such a nice i had to turn it off i called the bloke back out he says the mother was knacked and i needed a new one . he put a new motor on it i pays him 250 pounds .but it is still dripping now he says i need a new pump witch will cause 80 pounds plus labor