We meet Helmut's colleague Abdul in person instead and he is very polite & helpful. Helmut is a great host and give us a bottle of sparkling wine and some soft drinks as welcome gift. He responses my enquiry quickly and gives me good suggestion.
The apartment is very spacious for two of us and the balcony view is fanatasic. The location is just 3 minutes from Sants station and we can take train from Madrid to Barcelona very conveniently as well as to airport for our departure.
Definitely a perfect choice at Barcelona and we really enjoy our stay here.