Dublin Bus has confirmed that from 9th September they will no longer issue change receipts on their services:
https://www.dublinbus.ie/News-Centre/General-News/Removal-of-the-refund-facility-on-board-bus-services/
We wish to advise customers that from 9 September, you will no longer be issued a ‘refund due’ receipt when you overpay for your journey with cash on board our buses. Instead, you will be issued with an ‘extra payment’ receipt that is non-redeemable.
What can I do now?
• Use a Leap Card – Leap Card is at least 20% cheaper than paying in cash and it’s more efficient
• Have the exact fare for your journey
• Redeem previously issued ‘refund due’ receipts from our Head Office, O’Connell Street
If you still overpay for your journey after 9 September, the extra change will go towards continuing to improve our services, and funding the Community Spirit Awards, an initiative that has helped almost 1,800 voluntary groups to date through unclaimed passenger change.
The removal of the ‘refund due’ facility is also consistent with the National Transport Authority’s welcome intention to move to cashless operations on all buses under the BusConnects programme. The National Transport Authority is responsible for all aspects of the regulation of fares and ticketing.
It's strongly expected that the same policy will apply on Go-Ahead.