Hi not trying to cost you loads of money but the only two worth considering are Bosch or NGK believe me I had two aftermarket units on my car which failed in short order, if you can get them off eBay all well and good the part number is on the side of your existing unit so that gets you in the game, try partsinmotion on eBay or the net, I strongly suspect your unit is gone as I found they usually last between 80-100k.
Steve.