I have had the same issue on connecting redemptions and have been in correspondence with QRPC about it for the past month or so. They wrote to me on Friday saying it was fixed, but when I tried to book I got the same error. We have corresponded some more over the weekend and they did seem genuinely sorry (definitely not cut and paste) that I was still having the same problem. Anyway, the route I was looking at is also now booking properly as of today, so hopefully that particular IT problem is now solved!