Thank you all for your responses.
Indeed I was charged full price. As mentioned, I purchased when logged in on the desktop site. As the first comment stated the displayed prices were the half price tickets by default, I believed the tickets I was purchasing were half price.. If you could mark please RolandP’s as most helpful answer, as I’m afraid others will make the same mistake I did.
I have now gone in and applied the half fare to myself and my co-passenger and can see the discounts applied. However, I have decided to sort out a refund when I arrive in Switzerland, as it’s too risky to buy new tickets and spend more money in case there is an issue or a refund is denied.
For those wondering, I purchased tickets in advance due to the exchange rate for my currency being at its lowest since last year.
Thanks very much,