I had the worst experience with Wizz Air

Having unfortunately been in this position several times before, I think that the airline model is to hope that you are not very persistent or a "dangerous professional" (see this post by Patrick McKenzie) – if you show signs of either of these things they are much more likely to take you seriously.

Some unasked for advice specific to your case:

• The taxi fare and compensation are separate matters – if there is a delay greater than three hours (this is not in the EC261 legislation proper, but the ECJ has confirmed it) then the airline must pay you compensation for your inconvenience. However, the refund of your taxi fare (which clearly is an additional expense you have incurred only because of the delay) is not compensation (or at least I think there is a strong argument for this).
• Wizz are required to explain in detail how they determined the arrival time – specifically, you can also request copies of the aircraft flight logs and other evidence that Wizz may have (a good way to waste their time, and you don't even have to intend to look at them).
• Note that the arrival time does not refer to the time when the plane landed! Rather, it refers to the time when at least one door of the aircraft has been opened (see this ECJ ruling – note: ECJ rulings on EC261 have been retained as UK case law, so still apply even after Brexit)
• You can certainly claim for a meal that you have purchased (refreshments only – e.g. alcohol is not counted as a refreshment) as Wizz do not dispute that you were delayed by more than two hours (in which case Article 6 Article 9 of EC261 applies), assuming that Wizz did not provide any refreshments/hospitality (having flown with Wizz before this seems exceedingly unlikely)

If you are persistent, in my experience, eventually the airline will find it more expensive to deal with you than to pay compensation. Wizz are worse than most, however, so if they are not responsive then you may need to contact the CAA (or their Italian counterpart).