Thank you guys, for the support! The transactions have been accepted in the network!

0.5 was correct and the previous was indeed 0.05. 0.5 was the total that i owed.

I think i can close this post.

(although it remains a mystery why core wasn't working in the first place)

A good, successful and healthy 2018 for all of you!

A grateful Peter

(I will have a look at Core again in 2018)