Delivery date

Been shop a lot via apple website and for the first time encounter this issue that the delivery date of my order has been changed. On 26/3 I place an order for iMac and the ETA of my order will be 11/4, therefore I’ve sold my old iMac and MacBook Air and waiting the new iMac for my work and study.

yesterday I’ve received an email from apple stated that the delivery date has been change to 29/4-11/5 which is one month later. Would like to ask, where I can write to apple regarding this matter?as I am kinda urgent need the new Mac for my work and study.