Snagging and cleaning have very little in common. Snagging is all about listing jobs still to be completed by the builders prior to official handover whilst cleaning is just that. Never heard of Snagging Overseas (Overseas is a relative term in itself and whilst I gather this company is based in Portugal their choice of name seems most odd)
Best suggestion would be to speak to a local RICS Chartered Surveyor and ask them to do the job for you. It wont be too expensive and should certainly pay for itself in terms of getting faults included in the builders 'still to do list' that others may just miss. Much better to trust in someone qualified to do the job. Surveyors also have to have full professional indemnity insurance cover whereas cleaners don't.
