A classic main dealer con.
I paid for them to do it once, they then insisted a year later I needed a brake fluid change - told me at booking, told me at check in (twice), called me to tell me during the service then told me again when paying. On collection I took the invoice from one year previous and asked, using my outside voice so the other punters might hear - “did you really change the brake fluid last year as indicated on this invoice and are therefore trying to scam me this year or, assuming I need it now - as you keep telling me, did you not bother changing it and just charged me for it?”.
All of a sudden it didn’t need changing. It was all just some silly mistake and of course they had done it when they charged me for it. (Spin for - we’re trying to scam you now, sir).
I can only imagine lots of people blindly agree to these scams