Your cable is probably hot b/c battery corrosion backed itself up under the insulation and into the cable. The corrosion increases the resistance, which puts a slow drain on the battery even when everything is off. I had exactly this same problem on another car, although it was after 12 years, not 4.

The advice to seek out a different mechanic and use a universal is reasonable. You might also consider doing it yourself, perhaps even with the OE part. Either way, you should do it.

You should also get the corrosion-prevention rings to go around the posts, and clean the posts every year at the least.