2003 Ford Fiesta

Noises problem
2003 Ford Fiesta Manual

Hi,

My Ford Fiesta's exhaust pipe is making banging noise and the management light flashes all the time and sometime (every 2-3 days) EAC Fail sign comes up and the car goes really slow no matter which gear you are in, but turning it off and then on helps for a bit.

But could someone tell me if all these problems are connected and how much will it cost to repair?