If I want to change the date a AY award ticket (booked as Aviso ticket on ba.com but with AY flight number), can I call AY to change the date? Or do I have to go through BA call center?

There is availability but I am a bit weary of cancelling the award on ba.com and immediately rebooking in case the airmiles do not credit back immediately. My understanding of AY J fares is that these are flexible and can be amended if there is availability,hence a thought it might be less problematic calling AY to do this.

Sorry,perhaps a question in the stupid category...