No, not really. You paid a membership fee, which is the right to call them when you need them, and for them to attend. They might word it as "your membership cost includes your fitting cost" but really it doesn't. Because they can't possibly know what it is you will need fitting later on in the year at the time you pay the membership fee. And if it was actually a fitting cost, you could reclaim that cost back at the end of the year since you've not had any fitting done.

Regardless of how it's worded, you pay the fitting charge in with the product. Why do you think batteries are 1.5x the price of the same battery you can buy in Halfords? Because there's a fitting charge lumped in with the "purchase" price.

Same as when you buy something that includes "free" postage. Postage is not free, it's just lumped in the the cost of the item you buy.