Numerous agents within MH have stated to me that anyone that purchased tickets before this change (I purchased in January) should have had their reservations honoured and that they were exempt from the fees.

The issue MH has relates to their change of booking systems together with not expending any effort into restoring these.

In my case the standard get-out of "we reserve the right to move you for operational reasons" doesn't apply as I was able to book the exact same seats.