Opodo complaint: OPODO refuses to refund, change my flight or provide a vocuher

The 4th of January 2021 with the value of 837.70 Euros, I booked a flight with OPODO from Lima to London via Madrid however not long after that, Peru was included in the Red List of Countries in England, which denied the entry of people who have been in Peru the previous 10 days.
In that scenario, I proceeded to call OPODO and ask for advice. They told me to keep the flight open so I can change it whenever I needed it.
I asked for a voucher, however they denied that option.
In the end I was able to go to England through Mexico, and I wanted to get a flight ticket back to Lima using the OPODO ticket I had available, I tried to change it since April, but they refused several times, so in August 2021 I had to book a flight through Iberia, if not I would have overstayed in England.
Now I want to use the OPODO flight to go to Madrid, since the last date to use it is 04Jan2022, even though I called them 4 times, the hung up the phone and gave me several excuses to change my flight.
Also they pretended to have an issue in the system but never solved my problem or get back to me via email, etc.
I feel like OPODO is some sort of scam and they just want to keep your money, I not only invested 837.70 euros, I also invested long calls, time, money for international calls and my peace of mind.
I feel like this company is unreliable and do not have any intention to help the costumers.
I also have evidence of all the times I’ve tried to reach them unsuccessfully.