Update.
The claims agency cancelled the case as TAAG in Lisbon never bothered responding to their final demands.
In the end I took them to Court in England using the London address they have on Companies House, they never bothered responding to the Court so I have a CCJ valid for 6 years against them only enforceable in the UK.
Nobody from TAAG is present at the London address they use so I am unsure as to what to do next. Maybe wait and see if they start a flight to LHR/LGW in the next 6 years?