Cancelling flights and not helping with alternative flights

Disgusting airline and they will soon follow in the footsteps of the other airlines that are out of business. They have cancelled a lot of their flights due to a strike, I accidentally cancelled mine on the system because it was giving an error when trying to change to a new flight, I contacted them as soon as I could and was told they cannot help and I must now pay double for a new flight, yet they originally say you can change without fees, but now because of their system I must incur fees and change the flight to another day. It is clear I’m just trying to find another flight, the one I’m wanting to book is the day before as that’s the only availability