Bajaj Finserv — Order cancellation taking too long

I have placed order by mistake while checking the products but there is no option for cancellation which is weird, as all ecommerce online stores have that, to cancel order customer have to go through weired time taking process

I called Called there customer support they told me politely be rest assured as I have send ur request on high priority and will be cancelled within 48 hrs
No cancellation is being done, I called again on next day, same story
I called again next day same story, meanwhile I am getting sms from seller about shipment, now in 2 days shipment will be delivered and yet no cancellation is done I also emailed them in reply they said 48 hrs,
Thing which bothered is that why there is no option for order cancellation to cancel order straight away from there itself, why customer have to wait for 48 hrs after calling and mailing them, and after that also my complaint is not yet resolved.
I haven't encountered any online shop which dnt have cancellation button on there web page or application