Customer service invoice not accepted in case of leasing return

I have leased a car for two years via a company CAF (I have illegiblely abbreviated the company name in order not to get any trouble here). These are leasing cars for athletes. At the handover of the FIAT branch in Düsseldorf, no service booklet was added, which was only later noticed. A friend also got a similar car, also without a service booklet. I then had the customer service done at AutoFit at the end of these 2 years. The rest was taken care of and I received an invoice as proof. When the car was returned to Fiat, I submitted it. I was then told that points mentioned above were missing and I was also charged with a KOMPLETTER customer service in addition to a small damage. I objected on the spot, but the FIAT man told me that he didn’t care about my objection, because he has a contract with CAF and he had a contract with CAF. This is what I tried to do, but in response, the invoice was almost uncommented, including debiting (by the leasing bank). In my opinion, this is all abzocke of the Fiat branch, since there were no service papers for both cars and was declared insufficient for both cars when checking the invoice of the customer service. The cost of spark plugs is 4x4Euro and the pollen filter is about 10 Euro. (Whichever I would pay, as something was really forgotten) In return, however, I am charged about 250 for a complete customer service, although oil changes, inspections etc. were carried out 3 weeks before. What do you think about it? Am I really wrong?