Mercedes needs a lot of things fixed. Help please?

[Lania_G]

I have an 03 Mercedes E500 it has 100K miles. I haven't driven it in a long time so I recently tried to jump start it but it won't start. The radio and stuff comes though. The dash says 2 things. It says "ESP not available" and it also says "Malfunction: Electrical Consumers Turned Off". Last time I drove it it was leaking gasoline (right where the gas tank is) and I took it to a place but they were very unhelpful. What could possibly be wrong? And I know it's hard to determine without actually seeing it, but about how much do you think it would cost to repair these things? Thank you!