they are charging him for it so they are not doing him a favour they are providing a chargable serviceSo, no, they are doing the OP a favor.
This is undeniable and you repeating it is a favour wont make it true
Ps I will do you a favour I will post your bike anywhere you want for £100 or drive you anywhere for £1 per mile. Decorate your house for £250 per day etc these are all favours apparently 😕
The favor was to not just fix the bike and charge him full price, as he asked them to do. Instead, they helped him with a warranty claim, and charged him much less. They didn't have to do that and it cost them money. In my book, they did him a favor. I would be grateful if a shop did that for me.
It did a business deal and charged him for it - if you want to call a business doing its business for money a favour than that is your choice
The excellent news is almost all business will do you favours in exchange for money ....aren't we all lucky we can collect on favours from businesses for money.