Online shopping a nightmare

I bought a 10l air fryer online at clicks and then 2 days later they advertised a 22l for R100 more, I emailed them on 29 March, to ask how I can do an exchange on the air fryer, they responded to me yesterday only to say that they will ask the online team how I can do the exchange, they dnt even know how to do an exchange and they take forever to respond to me, the sale on the 22l kitchen corture air fryer will be finished by the time they respond to me, how do u not have an exchange guideline on the online ordering system, and howcome when you email them the service consultant does not know how to arrange an exchange, Shahiema Basardien is the consultant who responded to me, I did tell her that they are taking too long to respond to me but she has not bothered replying to me, online shopping is a painful experiance and I regret buying this online now because I cant even get help to exchange it