That happened to me. I had a booking for Hnd Hel Dub. When the flight time was changed and summer schedule finalised, my original connection was no longer feasible. Airline called me and I agreed to reroute via London on a flight leaving on same day. It would have been a more expensive fare if I had booked the LHR connection initially as special fare was only available for Hel route. I was also offered choice to refund as it was an "involuntary" change. Reissued ticket showed a higher fare code for new flights.