It may be worth trying to negotiate with the solicitor re fee's.
ie. Agree to pay 2000€ 's to take the case to court and on the proviso they win the case PLUS, ALL costs, interest, compo etc.. etc... They then get the final agreed amount or %. (taken from the award) Similar to 'no win no fee'. If they don't want to talk. Move on. I wouldn’t pay 10000€'s up front.
Also remember , the solicitor, agent and the developer have acted illegally by not supplying you BG's for your money. ( I could be wrong but thought it was a legal requirement when purchasing a property in Spain.) So sue for that as well.
Really, if it's the same solicitor he should show some compromise on fee's for failing to ensure you got BG's. They are surely partly to blame for you having to now go to court.!
''Dear Lord, please help us ALL to resolve this mess quickly''