I am afraid that if the flight was really delayed because of weather you are not entitled to compensation according to EC261. You are of course entitled to rebooking, accommodation and meals. They could have booked you on Avianca, but I am afraid by law they are not forced to do it.

So, unless I am missing something (or the delay was not really because of weather), it looks like they have done the bare minimum they are supposed to do and it is unlikely that fighting for more compensation would get you anything (maybe something if you had to eat while waiting for them to arrange the hotel).