Check Engine Light On problems of the 2003 Ford Explorer Sport

In February of 2006, I took my 2003 Ford explorer in to have it fixed. At the time, my vehicle only had app. 36,300 miles on it. I had to have all the spark plugs replaced because they had gone bad. I was told the spark plugs should have lasted for 90,000 to 100,000 miles. In April of 2007, with app. 43,000 miles on the vehicle, the check engine light came on. I took it in for repair and was told the spark plug wires were arcing and were burned. I was told that the wires were routed badly and that they lay against hot areas of the car. I now have to replace all the wires. The garage has called all the dealers and distributors in my area for the wires and was told that they can't get the wires, that they seem to have been pulled off of the shelf. If the wires are routed badly and lay against hot things, I would think eventually that would start a fire. The garage is going to give me the old wires just in case I need them. I would think an investigation needs to be done to see if, in fact, the wires are routed badly and could start a fire.