If you use the online ticket system, you get charged the standard £1.25 booking fee per ticket. You then have (or had - might be too late now and collection-only) the option of either paying an extra £1 to have them posted to you or it’s free to go collect from the ticket office during their opening hours (or from Cheltenham by the look of it). So if you do it this way and have it posted, it’s costing you £2.25 on top of the face value of the ticket.
If you buy them over the phone then exactly the same but no booking fee. Ditto if you rock up to the ticket office in person (which is now back as an option) except that you obviously pick up the ticket then and there and don’t need it posting.
What is the incentive to use eTicketing rather than phone & collect/post, or face-to-face?