A report to Police is one option, the other is lodging a complaint with the BFSO (Banking and Financial Services Ombudsman).
Others with more experience in this area might be able to offer a checklist of steps to cover the best approach.
The first requirement before lodging any complaint is to ensure you have given adequate opportunity for the institution to fix up the matter under their own provisions ... and I would think you have done more than enough to satisfy that.
One suggestion - if you haven't already done so, write up a log of every action you have taken, dates and times, the response given - ANYTHING you can think of that demonstrates a problem has occurred, what it is, the efforts you have made to get it rectified and the response of the institution concerned.
Being detailed is very powerful - but you must be accurate. If you have an exact date and time, them note it. If you don't remember an exact time, then put an approximate time range eg between 3pm and 6pm. If you have an exact quote, then note it. If not, then write it in your own words saying something like "The message I got was ......".
The most efficient way to do this is to have a notepad in front of you when make calls, for example. Recording there and then will always result in the greatest accuracy possible.
Sadly, this advice can be applied to ANY dealings with eBay or Paypal. Keep notes on everything!