Car having problems after it went for service, where not only normal service was done, additional major work on engine mounting was also done and the dealer

On the 07th of October my Husband Victor Mbele, took our car X1 sDrive20d SAV registration FD27SVGP for normal standard service. after dropping the car, he received a call from the service adviser, explaining the dignoses in the car, which exceeded normal service, including a major work to done on the engine mounting. from the list of diagnoses done we choose not replace tire only with BWM, opted to do it with tire service providers. the car was booked in since the 07th of October 2021 and only collect on the 12th of October 2021, total cost of 26611.66 including vat, we paid 20650, because we did not change tires there. few days (3 day) after collecting the car, the car started having problems of hard star, and Dip beam failure, my husband call the dear to inform them about the challenges we had with car just after major work was done in the car, he was told to book the car, and bring it back so they can check it. in from mid-October until the 26 November 2021, I was travelling (Zambia, Mauritius, Ghana, and Captown) and could not fine an open day to book the car. finally, on the 29th of November 2021, the BMW fountain gave us the 1st of December to bring the car. this morning I took the car in, and found a service adviser by the name of Brenda and she said I should pain diagnosis fees of R311.00 and I asked her why I should be paying the fees for the issues that could have been a result of the major work done on the car, then she told me they cant assist if I can not pay diagnosis fees. but I really don't understand why I should pay another diagnosis fee on top of the diagnosis done when I took the car in for service, and it started having problems just after they dome major work on the engine, and battery was disconnect, I had to reset time on car as an indication that it was disconnected. today they said they told my husband that battery needed attention, and this was never communicated on the phone, as diagnoses and quotation was confirm telephonically, and I asked her why this was not included on the initial quotation of 26k? because we accepted every thing that was diagnosed except the 2 tires replacement, I did not get the aswear, hnostly I find this so unfair, and I am not ready to another fee to dignose a car, that has just been fully serviced, paid over 20k , after few days of service the car can't start.