Hi - sorry to hear things seem to be going from bad to worse for you.
If it has an abta mark on the paperwork then ask the questions :
why is it on there - if not really covered you need to go down the line of trades description and the fact no declaration was made ie they did not specify that this particular holiday was not abta covered so why is it in the paperwork
why did they not disclose the holiday is not abta covered - it should be part of their disclosure statement like the bit about having a six month valid passport etc
after every conversation make notes and if at all possible just list them and email them to Ola Customer Service stating points discussed and what you expect next (they can't delete the emails) and everytime you phone just add to the original email
remind them all their phone calls are ' recorded' and by law you have access to these too - all this should do is remind them they have a record of all you discuss so next time when they claim not to know what you're talking about jolt their memories
ask the question- Do you want to ensure this problem is sorted out without me having to inolve third parties? hopefully pushing the representative to take ownership of the probelm and sort it rather than being the name being blamed when you take it further
Ultimately no company likes to give refunds but stand your ground try to have all the info at hand and keep positive - they are only employees and they have someone to answer to so if they are rude unhelpful or just acting like d**ks then take their name and keep on emailing - jam the system by forwarding forwarding forwarding there is only so much email they can cope with
Hope this helps and I know you may have done this already but don't give up
Cheers
Bev