Issues with THY Ticket Cancellation Process

I purchased return tickets from THY with a friend, but they canceled the return tickets for their own reasons. We've been on the waiting list for about a month and have respected the process. During this time, we were assured that there would be no problem with our outbound tickets and that we could travel comfortably. However, when we tried to check in on the last day, we were told that due to the sequential flight rule and the uncertainty of our return tickets, we couldn't check in for the outbound flight either. This situation has caused significant financial and emotional losses. Additionally, the lack of a proper complaint channel and the absence of a solution have added to the frustration. The main issue is that we bought the tickets using miles, and we were told that the waiting list would take longer. We understood this, but we were also informed that we could change the tickets by adding extra miles or money. Now, they are saying this is not possible. Every time we speak with them, we encounter new information and inconsistencies.