That’s correct. They were upgraded and the upgrade fee was tacked onto the car. The set price to upgrade from a 60D to a 75D is $4,000 last time I checked on a MX. $2,000 on a 60D.
Tesla would not refuse a software only upgrade. It doesn’t cost them a thing. It’s all done over the air, no SC trip needed. You log onto your Tesla account and click purchase. It triggers an update to your car. The end. I’ve done this on my car. The only reason you’d go to the SC is to get a new badge..if you care.
Now there’s a separate issue. Upgrading from a 60D to a 75D removes the top speed limiter. But it does NOT uncork the vehicle. Uncorking the vehicles requires a SC visit and configure update. In 2017, SCs would uncork a car out of goodwill but it was only eligible for 75Ds and not 60Ds. So a bunch of people bulked their upgrades and uncorking together (I am one of them)
Fast forward to now. That goodwill is reportedly ended. Some people are reporting that despite upgrading to a 75D, Tesla no longer uncorks the car after. It doesn’t mean it can’t be done, but depending on the SC they may not be willing to do it.