Malloh06

Hi Everyone, I have a an issue with my 2005 bmw x5 4.4i V8. It has a DMe combustion misfire from different cylinders. I've changed the coil pack and spark plugs but that has not helped resolve the problem. I need urgent help fixing this issue. I live in South East london and took it to Stephen James BMw in Woolwich....they were absolutely useless. My car came out worse than it went it. Any recommendations of a garage or technician within or outer London who is good at fixing this?