I totally get your point and I do hope they change it, but you've got to look at their argument.
They've identified a high wear area and designed a nice little heel pad for you to use, you for whatever reason don't use it and have been resting it on the carpet instead. Your natural rotation and movement of the foot/heel has worn it out. Be that through their poor design in heel pad placement, your bigger than average feet or driving position. How fast you've worn it is determined by the type of footwear.
Any manufacturer will say their product has a X life under average conditions and it stands to reason 10000 girls running on a carpet with ballet shoes is going to wear it out a lot less than 10000 workmen doing it in concrete encrusted hobnail boots. The carpet isn't designed for your heel, that's what the pad is for. They'll just claim you've worn it prematurely and should have either adapted your driving/foot position to utilise the pad or given they offer mats for sale to protect against this, advise that's what you should have bought to do so... they'll say the hole didn't suddenly happen, you should have seen what was occurring and taken appropriate action. You've a duty of care to look after your own stuff.
Your best argument is the heel pad design is not fit for purpose. Get every owner to photograph their foot position and tell you their foot size. If it isn't 'average' then it isn't fit for purpose.