Unfair treatment, outdated online system and delayed refund

Made bookings for international flights end August 2023, all passports were valid. Travelstart system did not flag/caution any passports nor expiry dates yet they took full payment. All visa req were in order. On departure airline booking system rejected one passport due to only 5 months valid. Sent an email to travelstart to cancel one pax flight before dep. Airline also advised that I can get the return leg refund. The contact centre is in India and seemingly English or interpretation of it is an issue as they've been misquoting/delaying my refund. I've dealt with 6 diff agents. They say it's the airline but I got the email from airline confirming the return leg refund. These online systems should be equipped to flag such issues like a travel agent and the airline check in systems do. I will never use travelstart again. To make matters worse their contact centre is online and best response time is in 24 hours, no direct human engagenent interface. With most int flights shorter than 24 hrs, this doesn't help at all...