UK car rental pre-authorization release

I have been battling for nearly 3 months now to get any sort of investigation into the reversal of funds (reversal of £200) on a car rental pre-authorization in the UK. The pre-authorization was done on the 19th of December 2019 was released on the 2nd of January 2020 per Budget/Avis UK. My query has been passed onto a different department with the one saying it's the other's responsibility. I've had a bank account with them for as long as I can remember, most probably 35+ years and would expect better service. WHERE TO FROM HERE?!?